question: What sentence would provide a factual answer to this question: "A long time ago, the Grand Canyon was"

answer: the Grand Canyon was formed by the Colorado River flowing over long periods of time

question: What sentence would provide a factual answer to this question: "In the desert, a hawk may enjoy an occasional"

answer: hawks eat lizards

question: What sentence would provide a factual answer to this question: "This would be associated with a lack of sunlight:"

answer:
a cavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone