public static IChoice getChoiceObj(string choice)
 {
     IChoice objChoice = null;
     if(choice.ToLower()=="car")
     {
         objChoice = new Car();
     }
     else if (choice.ToLower() == "bike")
     {
         objChoice = new Bike();
     }
     else
     {
         objChoice = new InvalidChoice();
     }
     return objChoice;
 }