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: Which adaptation helps a bird fly?  
 (A) larger feet (B) bigger eyes (C) longer beaks (D) hollow bones

Output: D


Input: Consider Input: Shale is a sedimentary rock that can be metamorphosed into slate by  
 (A) cementation. (B) chemical weathering. (C) sedimentation. (D) increased pressure.

Output: D


Input: Consider Input: Students notice that in the fall leaves of sugar maple trees turn red, but the leaves of black oak trees turn brown. The students are making  
 (A) an observation (B) a conclusion (C) a prediction (D) an inference


Output: A