Q1: Fill in the blanks in each of the following statements: a. If a class contains at least one abstract method, it’s a(n) class. b. Classes from which objects can be instantiated are called classes. c. involves using a superclass variable to invoke methods on superclass andsubclass objects, enabling you to "program in the general." d. Methods that are not interface methods and that do not provide implementations must bedeclared using keyword . e. Casting a reference stored in a superclass variable to a subclass type is called.