What is code refactoring?   Group of answer choices   A)None of the options are correct.   B) It is changing implementation of a method or constructor of a class, while leaving the declaration the same, allowing all users of that class to continue using the class without noticing the change.   C)It is abstracting a class so that common elements with another class are moved into the abstract class that both classes extend.   D) It is declaring all the methods that need to be supported in an interface. This guarantees that all classes implementing this interface will support those methods.

3. (10) Given below is the CRC diagram for a Circle ADT. Give the class definition and function definitions for this ADT. Circle - int r // radius // Constructors + Circle( int ) // Mutator + void setR( int) II Accessors + int getR( ) + int area( )

(JAVA) What is the benefit of an abstract class?   Group of answer choices   A) There is a guarantee that all classes that inherit from the abstract class have the methods and fields of the abstract class.   B) They cannot be instantiated, so you only need to write the code for the fields and methods that are common to all classes that extend it. You also need to initialize those fields in a constructor.   C) All choices are correct.   D) All classes that extend the abstract class will automatically inherit all the methods from the abstract classes without need to implement them again.

(JAVA) Create a class hierarchy to represent the different types of employees in an office who have the following job titles: manager, assistant, salesperson. Write an abstract base class called Employee that declares an abstract method: signature double calculateSalary() This class must also define the following attributes: name (String type), enrollment (String type) and base_salary (double type). Use encapsulation and provide a constructor that receives the corresponding values ​​to be stored in the respective attributes. This abstract class must be extended by the other classes representing the types of employees, so the classes Manager, Assistant and Salesperson must be written. In each class you must override the method calculateSalario so that the salary calculation is done like this: The manager receives twice the base_salary, the assistant receives the base_salary and the salesperson receives the base_salary plus a commission defined in the constructor of his class. Create a…