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: The nucleus of MOST atoms consists of  
 (A) neutrons only (B) protons and neutrons (C) protons and electrons (D) neutrons and electrons

Answer: B


Question: What happens when water flows over a rock for a long period of time?  
 (A) erosion (B) flooding (C) breakage (D) evaporation

Answer: A


Question: Soil erosion can be best prevented by  
 (A) removing grass from the steepest slope. (B) building terraces into the sides of a slope. (C) heavily watering the vegetation on the slope. (D) increasing the slope of the land by adding more soil.

Answer:
B