A good answer might be:

Yes. A child can have only one parent, but a parent can have any number of children.

Is-a Relationship

The picture shows a parent class and a child class. The line between them shows the "is-a" relationship. The arrow points to the parent class from the child class. The picture can be read as "a Ford is-a automobile."

The clouds represent classes. That is, the picture does not show any particular automobile or any particular Ford, but shows that the class Ford is a child of the class Automobile.

Inheritance is between classes, not between objects.

A parent class is a blueprint that is followed when an object is constructed. A child class of the parent is another blueprint (that looks much like the original), but with added features. The child class is used to construct objects that look like the parent's objects, but with added features.

QUESTION 3:

How many objects of a given class can be constructed? (Hint: how many houses can be build from one blueprint?)