Suppose Animal is an interface that specifies a single method

Question

Suppose Animal is an interface that specifies a single method - speak. Now suppose the Dog class implements the Animal interface. In addition to the speak method, the Dog class also has a method called wagTail. Now consider the following code. 
Animal a = new Dog();
A=wagTail();
Which of the following is true about this code?
A) It will result in a compile-time error.
B) It will result in a run-time error.
C) It will call the speak method defined in the Animal interface.
D) It will call the wagTail method defined in the Dog class.
E) none of the above are true.

Quizplus · Accepted Answer

This code will result in a compile-time error since the Animal interface does not specify a wagTail method. This compile-time error can be avoided by explicitly casting a as a Dog when calling the wagTail method.