instruction:
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:
Which term best describes the nature of all light waves?  
 (A) longitudinal (B) transverse (C) compressional (D) magnetic
answer:
B


question:
Rat snakes, Elaphe obsoleta, are a species made of many distinct populations in different areas. Each of the populations has different markings and colorings. Where would rat snakes most likely be gray?  
 (A) in a forest (B) in a swamp (C) in a gravel pit (D) in a corn field
answer:
C


question:
What do ice, a rock, and a piece of aluminum have in common?  
 (A) They are all solids. (B) They are all liquids. (C) They are all minerals. (D) They are all elements.
answer:

A