You have defined a class named Invoice that contains two non-static private fields, invoiceNumber and amount. The class also contains a non-static public function that displays the amount; the...

You have defined a class named Invoice that contains two non-static private fields,

invoiceNumber and amount. The class also contains a non-static public function that

displays the amount; the function’s prototype is void showAmount();. When you write

a main()function and declare one Invoice object named anInvoice, you can display

the object’s amount field with the statement ___________ .

a. cout

b. cout

c. cout

d. None of the above