The characteristic response of plants to sunlight—growing toward the light—is called positive phototropism. knowing that "trop" is the greek word for "turn," explain why this is an excellent term for this phenomenon.

Positive phototropism is an excellent term for the phenomenon because it explains how plants grow in the direction of sunlight. 

The word phototropism can be broken down into three meaningful components: photo+trop+ism

1. Photo- This a root word which means "light"
2. trop- Greek word which means "turn"
3. ism- This is a suffix which refers to "a process or theory".

In this way positive (affirmative) phototropism means "the process of moving towards the light".