Juanita is training for a triathlon, a timed race that combines swimming, biking, and running.

Consider the following sentence: Juanita has only 20 hours this week that she can devote to training. Each hour she spends swimming is an hour that she can't spend biking or running.

Which basic principle of individual choice do these statements best illustrate?

A:Juanita can use time most efficiently by spending the same amounts of time on swimming, biking, and running.

B:People face trade-offs

C:People usually exploit opportunities to make themselves better off.

D:Juanita has an incentive to spend more time on swimming than on biking or running.

B. People face trade-offs

Explanation:

Opportunity cost refers to the benefits foregone of a non chosen alternative when another alternative is chosen.

In the given case, time is a scarce resource and is limited. Within the limited time, Juanita can either perform any of the three activities or different combinations of the three activities.

To perform one activity more than others, requires sacrifice of time from other activities which means one can be taken up only at the expense of another. This represents a trade off wherein if one wants more of something, it requires corresponding sacrifice of something else.

Since Juanita's efficiency is not provided in absolute terms i. e measurable terms, the given situation corresponds to a state of a trade off.