instruction:
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:
Some kinds of fish live most of their lives in salt water but lay their eggs in freshwater. Their ability to survive in different environments is an example of  
 (A) adaptation (B) developmental stages (C) a habit (D) selective breeding
answer:
A


question:
If a student playing the drums hits the drums with greater force, the sound would be  
 (A) quieter. (B) louder. (C) lower in pitch. (D) higher in pitch.
answer:
B


question:
The human stomach is protected from self-digestion by a layer of  
 (A) bile. (B) mucus. (C) muscle. (D) white blood cells.
answer:

B