You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.
--------
Question: Which of these warms most of the air, water, and land on Earth?  
 (A) Coal (B) Electricity (C) Sunlight (D) Wind

Answer: C


Question: Ella waves good-bye from the bus. What body system pulls on bones to let Ella wave her arm?  
 (A) muscular system (B) nervous system (C) digestive system (D) circulatory system

Answer: A


Question: Which of these natural events occurs at time intervals that are the most regular?  
 (A) drought and flooding (B) high tides and low tides (C) clear skies and cloudy skies (D) hot weather and cool weather

Answer:
B