Which of the following is/are a true statement about 1 mole samples of oxygen,
 hydrogen, and nitrogen gas at STP?
 I. Only oxygen and hydrogen are diatomic molecules.
 II. All 3 samples occupy the same volume.
 III. All 3 samples have the same mass.
 A) I only
 B) II only
 C) I and II only
 D) II and III only
 E) I, II and III