Ricardo eats 20 pieces of sushi on a Friday night. When he eats the 21st piece, he starts to feel nauseous and realizes he probably should not have eaten the last piece. This suggests that for Ricardo the
◦ marginal utility of the 21st piece of sushi is positive and increasing.
◦ marginal utility of the 21st piece of sushi is negative.
◦ total utility of pieces of sushi is increasing.
◦ total utility of pieces of sushi is increasing by larger and larger increments.