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.

[EX Q]: Which would most likely be the characteristic of an object with a small volume and large mass?  
 (A) high density (B) low pressure (C) low viscosity (D) high temperature
[EX A]: A

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

[EX Q]: Which tool should a student use to examine spots on a frog?  
 (A) thermometer (B) hand lens (C) graduated cylinder (D) magnet
[EX A]:
B