Let MUS be the marginal utility of a sandwich, MUH be the marginal utility of a hot dog, PS be the price of a sandwich, and PH be the price of a hot dog. When the price of the goods is zero, Pat eats a sandwich. When Pat has to pay, she eats a hot dog. When Pat has to pay, which of the following is necessarily true?
(A) MUS = MUH = PS = PH
(B) (MUS / PS) > (MUH / PH)
(C) PS < PH
(D) PS > PH
(E) MUS = 0