Please answer the following question by reasoning step-by-step.
If one needed the bathroom they needed a key, to get it they had to also buy something from the what?\nOptions:\n- school\n- convenience store\n- rest area\n- mall\n- theater

convenience store
Convenience store is a small retail shop.

Convenience store sells items like toiletries, newspapers, etc.

One might need toiletries to get to a bathroom.

.

Thus, the answer is convenience store