Maria is training for a triathlon, a timed race that combines swimming, biking, and running. Consider the following sentence: Maria 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. Maria has an incentive to spend more time on swimming than on biking or running.
b. People usually exploit opportunities to make themselves better off.
c. Maria can use lime most efficiently by spending the same amounts of time on swimming, biking, and running.
d. People face trade-offs

D

Explanation:

Maria's time (resource) is limited so she has to choose between activities. This is known as trade off. Due to unlimited wants and limited resources available to fulfil the needs, humans must choose between activities.

This concept of trade off also gives rise to opportunity cost

opportunity cost is the cost of the next best option forgone when one alternative is chosen over other alternatives

If Maria swims, she forgoes the opportunity to go bike riding or running

the answer would be voluntary exchange -

"the act of buyers and sellers freely and willingly engaging in market transactions. moreover, transactions are made in such a way that both the buyer and the seller are better off after the exchange than before it occurred."

hope this : )

-shy

answergoing to the symphony;