Creating a chained dropdownlist using AJAX and XML

<?xml version="1.0" encoding="utf-8" ?>

<Motors>
  
  <!-- List of Available Cars (Companies)-->
  <motoc mcid="0" mcname="(Select)"></motoc>
  <motoc mcid="1" mcname="Tata"></motoc>
  <motoc mcid="2" mcname="Maruti"></motoc>
  <motoc mcid="3" mcname="Honda"></motoc>
  <motoc mcid="4" mcname="Hyundai"></motoc>
  <motoc mcid="5" mcname="Toyota"></motoc>
  
  <!-- List of Available Bikes (Companies)-->
  <motob mbid="0" mbname="(Select)"></motob>
  <motob mbid="1" mbname="Honda"></motob>
  <motob mbid="2" mbname="Bajaj"></motob>
  <motob mbid="3" mbname="TVS"></motob>
  <motob mbid="4" mbname="Yamaha"></motob>

  <!-- List of Cars Brands (Models)-->
  <motocb mcbid="1" mcid="1" mcbname="(All)"></motocb>
  <motocb mcbid="2" mcid="1" mcbname="Indica"></motocb>
  <motocb mcbid="3" mcid="1" mcbname="Indigo"></motocb>
  <motocb mcbid="4" mcid="1" mcbname="Safari"></motocb>
  <motocb mcbid="5" mcid="1" mcbname="Nano"></motocb>
  <motocb mcbid="6" mcid="1" mcbname="Sumo"></motocb>
  <motocb mcbid="7" mcid="1" mcbname="Sierra"></motocb>
  <motocb mcbid="8" mcid="1" mcbname="Jaguar"></motocb>
  <motocb mcbid="9" mcid="1" mcbname="Land Rover"></motocb>
  <motocb mcbid="10" mcid="2" mcbname="(All)"></motocb>
  <motocb mcbid="11" mcid="2" mcbname="800"></motocb>
  <motocb mcbid="12" mcid="2" mcbname="Zen"></motocb>
  <motocb mcbid="13" mcid="2" mcbname="Alto"></motocb>
  <motocb mcbid="14" mcid="2" mcbname="Ritz"></motocb>
  <motocb mcbid="15" mcid="2" mcbname="Wagon R"></motocb>
  <motocb mcbid="16" mcid="2" mcbname="Swift"></motocb>
  <motocb mcbid="17" mcid="2" mcbname="Eco"></motocb>
  <motocb mcbid="18" mcid="2" mcbname="Estilo"></motocb>
  <motocb mcbid="19" mcid="3" mcbname="(All)"></motocb>
  <motocb mcbid="20" mcid="3" mcbname="City"></motocb>
  <motocb mcbid="21" mcid="3" mcbname="Civic"></motocb>
  <motocb mcbid="22" mcid="3" mcbname="Acura"></motocb>
  <motocb mcbid="23" mcid="3" mcbname="Accord"></motocb>
  <motocb mcbid="24" mcid="3" mcbname="Insight"></motocb>
  <motocb mcbid="25" mcid="3" mcbname="CR-V"></motocb>
  <motocb mcbid="26" mcid="4" mcbname="(All)"></motocb>
  <motocb mcbid="27" mcid="4" mcbname="Santro"></motocb>
  <motocb mcbid="28" mcid="4" mcbname="Sonata"></motocb>
  <motocb mcbid="29" mcid="4" mcbname="Accent"></motocb>
  <motocb mcbid="30" mcid="4" mcbname="Verna"></motocb>
  <motocb mcbid="31" mcid="4" mcbname="i10"></motocb>
  <motocb mcbid="32" mcid="4" mcbname="i20"></motocb>
  <motocb mcbid="33" mcid="4" mcbname="Tucson"></motocb>
  <motocb mcbid="34" mcid="5" mcbname="(All)"></motocb>
  <motocb mcbid="35" mcid="5" mcbname="Innova"></motocb>
  <motocb mcbid="36" mcid="5" mcbname="Corolla"></motocb>
  <motocb mcbid="37" mcid="5" mcbname="Fortuner"></motocb>
  <motocb mcbid="38" mcid="5" mcbname="Sera"></motocb>
  <motocb mcbid="39" mcid="5" mcbname="Etios"></motocb>
  <motocb mcbid="40" mcid="5" mcbname="Prius"></motocb>

  <!-- List of Bikes Brands (Models)-->
  <motobb mbbid="1" mbid="1"  mbbname="(All)"></motobb>
  <motobb mbbid="2" mbid="1"  mbbname="CB Twister"></motobb>
  <motobb mbbid="3" mbid="1"  mbbname="Aviator"></motobb>
  <motobb mbbid="4" mbid="1"  mbbname="Unicorn"></motobb>
  <motobb mbbid="5" mbid="1"  mbbname="CBZ"></motobb>
  <motobb mbbid="6" mbid="1"  mbbname="Shine"></motobb>
  <motobb mbbid="7" mbid="1"  mbbname="Hawk"></motobb>
  <motobb mbbid="8" mbid="1"  mbbname="Dream"></motobb>
  <motobb mbbid="9" mbid="1"  mbbname="Ascot"></motobb>
  <motobb mbbid="10" mbid="2"  mbbname="(All)"></motobb>
  <motobb mbbid="11" mbid="2"  mbbname="Pulsar"></motobb>
  <motobb mbbid="12" mbid="2"  mbbname="Caliber"></motobb>
  <motobb mbbid="13" mbid="2"  mbbname="Wind"></motobb>
  <motobb mbbid="14" mbid="2"  mbbname="Platina"></motobb>
  <motobb mbbid="15" mbid="2"  mbbname="Discover"></motobb>
  <motobb mbbid="16" mbid="2"  mbbname="CT 100"></motobb>
  <motobb mbbid="17" mbid="2"  mbbname="Boxer"></motobb>
  <motobb mbbid="18" mbid="2"  mbbname="Avenger"></motobb>
  <motobb mbbid="19" mbid="3"  mbbname="(All)"></motobb>
  <motobb mbbid="20" mbid="3"  mbbname="Apache"></motobb>
  <motobb mbbid="21" mbid="3"  mbbname="Flame"></motobb>
  <motobb mbbid="22" mbid="3"  mbbname="Jive"></motobb>
  <motobb mbbid="23" mbid="3"  mbbname="Stat City"></motobb>
  <motobb mbbid="24" mbid="3"  mbbname="Victor"></motobb>
  <motobb mbbid="25" mbid="3"  mbbname="Star"></motobb>
  <motobb mbbid="26" mbid="4"  mbbname="(All)"></motobb>
  <motobb mbbid="27" mbid="4"  mbbname="RX 100"></motobb>
  <motobb mbbid="28" mbid="4"  mbbname="Nouvo"></motobb>
  <motobb mbbid="29" mbid="4"  mbbname="Mio"></motobb>
  <motobb mbbid="30" mbid="4"  mbbname="Sirius"></motobb>
  <motobb mbbid="31" mbid="4"  mbbname="Chappy"></motobb>
  <motobb mbbid="32" mbid="4"  mbbname="Giggle"></motobb>
  <motobb mbbid="33" mbid="4"  mbbname="Zuma"></motobb>
  
</Motors>