In this task, you are given a question and a corresponding answer. Your task is to generate a fact statement that is useful in answering the given question.

Question: It's most likely to rain when the color of the sky looks? Answer: dark and Silvery.
grey clouds appear before precipitation

Question: Which is the likeliest part of a pencil to have been mined? Answer: the lead.
pencil lead contains mineral graphite

Question: Before their trip to the Amazon Bill and Jane had sharp metal objects stuck into their arms by a doctor.? Answer: they wanted to avoid contracting something.
vaccines can help prevent illness