Any suggestion on whats worng with the codes?

#include <stdio.h>
#include <stdlib.h>
void pH(float *s);
void temp(float *s);
void co2(float *s);
int i=0;

struct Smart_Master
{
float pH, temp, co2;
};

int main()
{
    int c;
    printf("\aSMART MASTER GREENHOUSE\n");
    printf("\nlets get started!\n");
    system ("pause");
    system ("cls");
    printf(" \nWHAT DO YOU WANT TO KNOW?\n");
    printf("____________________________\n");
    printf("\n1.SOIL STATUS \n\n2.TEMPERATURE STATUS \n\n3.CONCENTRATION OF C02 \n\n");
    scanf("%d",&c);
    struct Smart_Master data[10]={};
    switch(c)
    {
    case 1:
        pH(data[i].pH);
        break;

    case 2:
        temp(data[i].temp);
        break;

    case 3:
        co2(data[i].co2);
        break;
    }


    return 0;
}
void pH(float *s)
{
  printf("hii\n");
}
void temp(float *s)
{

}
void co2(float *s)
{

}