Suppose that a utility-maximizing consumer is usually purchasing two complements, ketchup (a normal good) and french fries. Suppose that the price of ketchup increases and as a result the quantity purchased of french fries decreases, ceteris paribus. We can thus say that french fries are..

A. necessities

B. of a type which cannot be determined

C. luxuries

D. normal goods

(*I selected D and it said the answer was incorrect*).