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.

Input: Consider Input: When iron combines with oxygen in a moist environment, rust forms because of a  
 (A) chemical reaction. (B) physical reaction. (C) change in density. (D) change in temperature.

Output: A


Input: Consider Input: A shallow container of salt water is placed in sunlight for a day. Which is the most likely result?  
 (A) All of the mixture will evaporate. (B) The salt will keep the water from evaporating. (C) The salt will separate from the water and float at the top of the container. (D) Only the water will evaporate and the salt will remain in the container.

Output: D


Input: Consider Input: When Dennis operates his lawnmower, he notices the engine makes a lot of noise. He also notices that the engine gets very hot. Which best describes the heat and noise generated from the lawnmower?  
 (A) a change in phase (B) thermal expansion (C) an increase in entropy (D) mechanical advantage


Output: C