If class Dog has a subclass Retriever, which of the following is true?

A) Because of single inheritance, Dog can have no other subclasses.
B) Because of single inheritance, Retriever can extend no other class except Dog.
C) The relationship between these classes implies that Dog "is-a" Retriever.
D) The relationship between these classes implies that Retriever "has-a" Dog.

Single Inheritance

Single Inheritance is a feature of object-oriented programming where a class can inherit properties and methods from only one superclass.

Subclass

A class that inherits from another class, known as superclass, and can have additional properties or methods.

Dog

A domesticated carnivorous mammal known for its loyalty and companionship as a pet, belonging to the species Canis lupus familiaris.