Answer:
Geologists search rivers, mountains, and caves for clues about how and when the Earth was formed.
Explanation:
This would be an important idea to include in your summary because it contributes to the central idea of the entire passage. The passage is about the work of geologists, and this sentence/idea is the main idea.
the last 2 because the first two are just saying they’re against that statement
Well saying dunno is an error in formal/academic writing. In academic writing you would have to write, i do not know, though.
Explanation:( I don't know sorry
