question: What sentence would provide a factual answer to this question: "Roads need repaved in spring because"

answer: cycles of freezing and thawing water cause ice wedging


question: What sentence would provide a factual answer to this question: "How many ecosystems does the earth contain?"

answer: the Earth contains many ecosystems


question: What sentence would provide a factual answer to this question: "If a sand grain is in a tree house unexpectedly, a likely culprit responsible for its movement is"

answer:
wind carries sand from one place to another place