The diet of a Triggerfish includes sea urchins overtime the increase use of recreational boats in areas inhabited by Triggerfish could result in triggerfish A. learning to eat stonefly larvae.

B. dying off because of lack of plants.

C. moving to areas with greater food supply.

D. decreasing in population.

D. decreasing in population.

Explanation:

Triggerfish are the brightly colored fish and sea urchins are the globular animals, echinoderms. Triggerfish eat sea urchins for their survival.

An increase in the use of recreational boats over the area will damage the habitat of the triggerfish and also affect their food supply, it will result in a decreasing population of triggerfish. Due to lack of sea urchins and habitat disturbance, the Triggerfish population will decrease

Hence, the correct answer is "D. decreasing in population."