I'll give you a question, please answer with step-by-step reasoning process.
Where can you look up a number to a business when you don't have electricity?\nOptions:\n- power grid\n- equation\n- telephone book\n- math problem\n- roulette wheel

telephone book
A telephone book is accesible evn when there is no electricty.

A telephone book has numbers of various businesses.

.

So, the final answer is telephone book