A program contains a seven-element array that holds the names of the days of the week. At the start of the program, you display the day names using a subscript named dayNum. You display the same array values again at the end of the program, where you ________ as a subscript to the array.

a. Must use dayNum

b. Can use dayNum, but can also use another numeric value

c. Must not use dayNum

d. Must use a numeric constant instead of a variable