Let's think step by step! What ccurs when many muscles contract a little bit all at once?
Options:
- (A) heat production
- (B) heat loss
- (C) sweating
- (D) permineralization
- (E) hypothermia
- (F) resistance
- (G) cramping
- (H) heat energy
The thinking starts now:

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
Shivering occurs when many muscles contract a little bit all at once. Heat production is increased by shivering and non-shivering thermogenesis . Heat production occurs when many muscles contract a little bit all at once. The final answer: (A).