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.

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


[Q]: Sharpening a pencil and tearing paper are examples of physical changes. Which statement describes why these are physical changes?  
 (A) There is a change in how the objects are used. (B) There is a change in the appearance of the objects. (C) There is a change in the materials from which the objects are made. (D) There is a change in both the appearance of the objects and the materials from which they are made.
[A]: B


[Q]: Scientists dig in a dry area at the bottom of a mountain range. Fossilized shells of freshwater mussels are found in the area. Which is a likely conclusion that scientists will draw based on this evidence?  
 (A) Rivers once flowed through the area. (B) Volcanoes were once active in the area. (C) The ocean shoreline once reached this area. (D) Floods were a common occurrence in this area.
[A]:
A