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

She doesn't understand he's applying opportunity cost method

Explanation:

Opportunity cost is basically arranging your schedule from that which is of great importance to the next, till the least important. It is understood that most of our activities are not giving same energy, especially when we understand some better than the others, this is where opportunity cost comes in, allowing you to arrange all activities from that which needs much attention to that which needs less, this is what Andrew was doing that his wife needed to understand

acid rain is the answer