The correct answer is C. Thick, waxy coats become more common on a species of trees during a drought.
Explanation
Throughout history, plants have evolved to adapt to different climatic conditions and geographical characteristics. Therefore, different characteristics can be seen in plants such as large leaves to capture the sun's rays and obtain food from them, thick trunks to protect themselves from adverse weather conditions, thorns, among others. In the previous case, the best example of the evolution of plants that have waxy layers is the increase of this characteristic in times of drought, because the plants adapt to this condition to conserve water for long periods. According to the above, the correct answer is C. Thick, waxy coats become more common on a species of trees during a drought.