Which of the following decisions cannot be made at the margin?
a. whether to move to boston from chicago
b. whether to spend the day on saturday watching movies or going hiking
c. whether to spend your two-week vacation on the shore or in town
d. whether to order a pepperoni or a cheese pizza

D.) Whether to order a pepperoni or a cheese pizza is a decision that cannot be made at the margin.

Making decisions at a margin is merely considering an option on top of your made decision. Cost and Benefit is a factor in thinking in a margin.

You have already decided to move. Your marginal decision is whether to move to Boston from Chicago,

You have already decided to spend the day on Saturday. Your marginal decision is whether to watch a movie or go hiking.

You have already decided to have a two-week vacation. Your marginal decision is whether to spend it on the shore or in town.

You have decided to order a pizza. Any flavor of pizza will still make you spend money. So there is no marginal decision needed.