The sun was out and the temperature changing rapidly, it was really beginning to what?
Options:
- drop to zero
- increase
- cool down
- dropping quickly
- heat up Let's give stream of consciousness first:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
When the sun is out, the temperature begins to heat up. Temperature becomes heat up when it changes rapidly after the sun is out.
Therefore, the answer is heat up.