【正确答案】 A

【答案解析】[听力原文]
Narrator
Listen again to part of the lecture. Then answer the question.
Professor
Anyone guess why? Look at their names. What do you think iron meteorites consist of?
Female student
Mostly iron?
Professor
Yeah, iron and some nickel, both of which are metals. And if you"re trying to find metal?
Narrator
Why does the professor say this:
Professor
And if you"re trying to find metal?