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.

Proxima Centauri is the closest star to the Sun. Which units do astronomers most often use for the distance between Earth and Proxima Centauri?  
 (A) miles (B) meters (C) light years (D) astronomical units
C

The fusion reaction that fuels the Sun converts hydrogen into  
 (A) carbon. (B) iron. (C) neon. (D) helium.
D

When scientists publish papers describing the results and conclusions of their experiments, members of the scientific community should  
 (A) collect their own data and rewrite the paper. (B) evaluate the evidence in the paper. (C) accept the paper as fact. (D) ask the writer to write an alternate paper.

B