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 Input:
If a student gets a chemical splashed into an eye, what is the most appropriate first action to be taken?
(A) wipe it with a paper towel (B) call 911 for emergency services (C) have someone go get the school nurse (D) flush the eye with water at an eyewash station

Ex Output:
D

Ex Input:
All of the different organisms interacting in a pond make up
(A) a community (B) a population (C) the water cycle (D) the habitat

Ex Output:
A

Ex Input:
What is the smallest unit of an element that still has the properties of that element?
(A) an atom (B) a compound (C) an electron (D) a molecule

Ex Output:
A