What Must a Subclass Do to Modify a Private Superclass

Multiple Choice

What must a subclass do to modify a private superclass instance variable?

A) The subclass must simply use the name of the superclass instance variable.
B) The subclass must declare its own instance variable with the same name as the superclass instance variable.
C) The subclass must use a public method of the superclass (if it exists) to update the superclass's private instance variable.
D) The subclass must have its own public method to update the superclass's private instance variable.