A programmer is designing a BankAccount class. In addition to the usual information needed for a bank account, she would like to have a variable that counts how many BankAccount objects have been instantiated. She asks you how to do this. You tell her:

$($A$)$ It cannot be done, since each object has its own variable space.

$($B$)$ She should use a class constant.

$($C$)$ She should call a mutator method to change the nunticcounts variable held in each object.

$($D$)$ She should create a static variable and increment it in the constructor as each object is created.

$($F$)$ Java automatically keeps a tally. She should reference the variable maintained by Java.