Where can you look up a number to a business when you don't have electricity?
Options:
- power grid
- equation
- telephone book
- math problem
- roulette wheel
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
A telephone book is accesible evn when there is no electricty. A telephone book has numbers of various businesses. The final answer: telephone book.