To properly represent the relationship "Man has a best friend who is a Dog," we need to define a class that includes a private instance variable of type Dog to represent the best friend.
Let's go through each option to understand why it is correct or incorrect:
Option A) class Man extends Dog { }
This option is incorrect because it represents a class Man that extends a class Dog, which implies an inheritance relationship rather than a composition relationship.
Option B) class Man implements Dog { }
This option is incorrect because it represents a class Man that implements an interface Dog, which is not appropriate for representing a "has-a" relationship.
Option C) class Man { private BestFriend dog; }
This option is incorrect because it introduces a new class BestFriend, which is not necessary to represent the relationship. Additionally, the variable should be of type Dog, not BestFriend.
Option D) class Man { private Dog bestFriend; }
This option is correct because it represents a class Man that has a private instance variable bestFriend of type Dog, which properly represents the relationship "Man has a best friend who is a Dog."
Option E) class Man { private Dog }
This option is incorrect because it includes invalid syntax. It is not possible to use angle brackets in this manner.
Option F) class Man { private BestFriend }
This option is incorrect because it includes invalid syntax. It is not possible to use angle brackets in this manner.
The correct answer is D. This option is correct because it represents a class Man that has a private instance variable bestFriend of type Dog, which properly represents the relationship "Man has a best friend who is a Dog."