【正确答案】 C

【答案解析】[解析]
Narrator
Listen again to part of the lecture. Then answer the question.
Professor
Most of the rocks move in the same direction as the dominant wind pattern, from southwest to northeast. But some, and this is interesting, move straight west, while some zigzag... or even move in large circles. Hmmm... how can that be?
Narrator
What does the professor imply when he says this:
Professor
But some, and this is interesting, move straight west, while some zigzag... or even move in large circles. Hmmm... how can that be?