John really enjoys eating Nathan's hot dogs in New York City. His marginal utilities from the first three hot dogs he consumes are 200, 150, and 125, respectively. His total utiity when he consumes three hot dogs is: O a. 475. Ob. 350. Oc. 200. O d. 125. Alexandra notices that the marginal utility of working with a tutor seems to fal with each hour the tutor helps her study. If Alexandra keeps the tutor until her grade actually begins to fall, her marginal utility for the last hour of tutoring will be: a. negative. Ob. 0. Oc. immeasurable. Od. positive, but rising more slowly.