Question

Crystal is training for a triathlon, a timed race that combines swimming, biking, and running. Consider the following sentence: Because her pool sessions are helping her swim more quickly, Crystal plans to reduce by 1 hour per week the time she spends training on the bike and increase by 1 hour the time she spends in the swimming pool; however, her husband says that she should stop doing any biking and running and spend all 20 hours per week in the pool. Which basic principle of individual choice does Crystal's plan illustrate that her husband's advice does not?

(A) People usually exploit opportunities to make themselves better off.
(B) Resources are scarce.
(C) Many decisions are made on the margin.
(D) All costs are opportunity costs.

Answer 1

The correct answer is letter "C": Many decisions are made on the margin.

Step-by-step explanation:

Talking about margin implies considering the benefits over costs. Moreover, the benefits that could be received over the cost of sacrificing something useful. By considering spending one more hour swimming and sacrificing one hour biking, Crystal is implementing the margin principle. On the other hand, her husband is thinking more about opportunity costs which implies choosing one option and leave the rest behind -spend all the time training in swimming and stop biking and cycling.