What does an animal do when it becomes old?
Options:
- live long
- leave home
- feel pain
- eating
- sense fear in human
Please answer and provide answer explanation.

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
Feeling pain means to experience suffering. Old animals experience suffering. The final answer: feel pain.