Yvette 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, Yvette 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 Yvette'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.

The correct answer is the option D: All costs are opportunity costs.

Explanation:

To begin with, the fact that Yvette is looking forward to reduce only one hour of her training on the bike in order to add one hour to her training on the pool and later her husband says that she should use all her hours for the training in the pool is showing a situation where her husband's advice does not illustrate a basic principle of individuals choices that is that all the costs are opportunity costs and therefore that if she decides to do that then she would be sacrifying the time for the other trainings and that would not benefit her. So that is why she must choose to sacrifice time in one training to do another and so on.

answer; commerce clearing house;