Detailed Instructions: In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").
Q: Fact1: a planet rotating causes cycles of day and night on that planet, Fact2: Our bodies and senses adjust to the cycle of day and night so that we may work in the day and sleep at night., Question: Sleeping at night and working during the day is determined by what thing happening? (A) clouds forming (B) planet rotating (C) heat energy (D) dehydration (E) solar flares (F) animal reproduction (G) Animal survival (H) sweating
A:
B