Java Class Requirements

Question

In the following problem,

1. Which of the following is true regarding Java classes?
a) All classes must have 1 parent but may have any number of children (derived or extended) classes.
b) All classes must have 1 child (derived or extended) class but may have any number of parent classes.
c) All classes must have 1 parent class and may have a single child (derived or extended) class. d) All classes can have any number (0 or more) of parent classes and any number of children (derived or extended) classes.
e) All classes can have either 0 or 1 parent class and any number of children (derived or extended) classes.

I believed the answer would be e). I thought this because all classes can have at most 1 parent class or at least 0 (the Object class has no parent class). Furthermore, you can have any number of children (assuming integers greater than or equal to 0). The correct answer was a):

All classes must have 1 parent but may have any number of children (derived or extended) classes.

Does this mean that you can't consider the Object class to be a class?

Does the Object class have a parent?

Also, I recently asked another question on Java, also from this series of assignments (actually an optional test-review, not homework). Sorry for the two posts, but I didn't think it followed correct etiqutte to combine the questions into one post.