Answer:
C. Local winds are caused by the unequal heating of Earth’s surface within a small area.
Step-by-step explanation:
This is the main idea of the excerpt. In this excerpt, we learn that local winds are caused by the unequal heating of the Earth’s surface within a small area. This is the main point in the passage because it is the one that contains the most relevant information. The author includes the rest of the information in order to make the text more compelling and interesting.