When I am uploading data from excel to sql table columns it is generating an error like below.

SqlConnection con=new SqlConnection();
       con.ConnectionString  = ConfigurationManager.ConnectionStrings["db"].ToString();
       con.Open();
        string path = fileuploadExcel.PostedFile.FileName;
       
       string excelConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 12.0;";

        OleDbConnection excelConnection = new OleDbConnection(excelConnectionString);
        excelConnection.Open();
        OleDbCommand cmd = new OleDbCommand("Select [Question],[Choice1],[Choice2],[Choice3],[Choice4],[Ans],[Category] from [Sheet1$]", excelConnection);
       
OleDbDataReader dReader;
dReader = cmd.ExecuteReader(); SqlBulkCopy sqlBulk = new SqlBulkCopy(con);
 

    sqlBulk.ColumnMappings.Add("Question", "Qn");
    sqlBulk.ColumnMappings.Add("Choice1", "option1");
    sqlBulk.ColumnMappings.Add("Choice2", "option2");
 
    sqlBulk.ColumnMappings.Add("Choice3", "option3");
    sqlBulk.ColumnMappings.Add("Choice4", "option4");
    sqlBulk.ColumnMappings.Add("Ans", "ans");
    sqlBulk.ColumnMappings.Add("Category", "Q_Type");
    sqlBulk.DestinationTableName = "Questions";
    sqlBulk.WriteToServer(dReader);

excelConnection.Close();