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:
Which of the following units best represents the density of an object?  
 (A) kg (B) hr (C) m/s^2 (D) g/cm^3
answer:
D


question:
You wish to closely observe a small insect. Which tool is the best to use?  
 (A) a balance (B) a test tube (C) a telescope (D) a magnifying glass
answer:
D


question:
According to scientists, donkeys and horses share a common ancestor. Which evidence shows that the two organisms are related?  
 (A) Both are tall. (B) Both run fast. (C) They have the same diet. (D) They have the same bones in their limbs.
answer:

D