Which of the following operations do forward iterators have? a. overloaded operator+ to add an int value to the iterator to move the place the iterator points forward by the argument number of elements. b. overloaded operator* to multiply the iterator by an int value to move the place the iterator points by a number of elements equal to the argument. c. overloaded operator++ to move the place the iterator points forward by one element. d. overloaded operator-- to move the place the iterator points backward by one element.