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:
All of the following can become fossils except  
 (A) bones. (B) shells. (C) teeth. (D) rocks.
answer:
D


question:
The parts of plants that make seeds are the  
 (A) roots. (B) stems. (C) flowers. (D) leaves.
answer:
C


question:
Which gas is the most abundant in Earth's atmosphere?  
 (A) oxygen (B) nitrogen (C) water vapor (D) carbon dioxide
answer:

B