Answer the following statements true (T) or false (F)

a) All methods in an abstract class must be declared as abstract methods.
b) Invoking a subclass-only method through a subclass variable is not allowed.
c) If a superclass declares an abstract method, a subclass must implement that method.
d) An object of a class that implements an interface may be thought of as an object of that interface type.

1) False. An abstract class can include methods with implementations and abstract
methods.
2) False. Trying to invoke a subclass-only method with a superclass variable is not allowed.
3) False. Only a concrete subclass must implement the method.
4) True.