If you choose between two summer jobs, what is the one you do not choose called?

A. opportunity cost
B. decision at the margin
OR
C. opportunity at the margin

The answer is A. opportunity cost.

To understand why, let's break down the options:

A. Opportunity cost: This refers to the value of the next best alternative that you give up when making a decision. In this case, since you have two summer job options and you can only choose one, the job you do not choose becomes your opportunity cost.

B. Decision at the margin: This concept involves making decisions by comparing the costs and benefits of a little more or a little less of something. While this concept is relevant to decision-making, it doesn't directly refer to the job you do not choose in this scenario.

C. Opportunity at the margin: This option does not accurately reflect the concept being described. "Opportunity at the margin" is not a commonly used term, and it doesn't fit the given scenario.

Therefore, the correct answer is A. opportunity cost.