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 family will pay for their feud with their children's lives
'Plain english' is a writing style that gets straight to the point, clear, and straightfoward , common in goverment or business and communications.