You are given a science question (hard-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: Some bacteria use iron found in their systems as a means to guide their movement. Which stimulus most likely triggers this movement mechanism?  
 (A) magnetism (B) oxygen (C) light (D) heat

Output: A


Input: Consider Input: Students shake salt into a jar of water, and they shake pepper into a second jar of water. Which statement best compares the two jars?  
 (A) Only the salt and water is a mixture. (B) Only the pepper and water is a solution. (C) Both jars contain solutions. (D) Both jars contain mixtures.

Output: D


Input: Consider Input: A 0.20 kg softball travels 97 meters (m) south for 4.5 seconds (s). What piece of information distinguishes the velocity from the speed of the ball?  
 (A) The ball went south. (B) The ball flew for 4.5 s. (C) The ball traveled 97 m. (D) The ball has a mass of 0.20 kg.


Output: A