You are given a science question (hard-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: What part of the digestive system first causes chemical changes to food?  
 (A) teeth in the mouth (B) saliva in the mouth (C) enzymes in the stomach (D) enzymes in the small intestine

Answer: B


Question: One property of liquids is that they have a definite  
 (A) flexibility (B) temperature (C) volume (D) shape

Answer: C


Question: Felicia noticed how air temperatures were cooler and there were fewer hours of daylight during some of the seasons. Which of the following contributes to these seasonal changes?  
 (A) Earth rotates on its axis. (B) Earth revolves around the Sun. (C) The Sun has less energy in winter. (D) The Sun moves further from Earth in winter.

Answer:
B