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]: Sam looks into a fish pond and points at a goldfish. Sam's grandfather looks where Sam is pointing and tells Sam that the fish is actually in a different location. Which property of light explains why Sam's grandfather is correct?  
 (A) reflection (B) refraction (C) diffraction (D) absorption
[EX A]: B

[EX Q]: A meeting of scientists, called a symposium, occurs every year to share recent research about the atmosphere of Earth. This symposium mainly serves which purpose in science?  
 (A) to test research methods used by other scientists (B) to develop questions about space research (C) to discuss the meaning of new discoveries (D) to explain gas properties to the general public
[EX A]: C

[EX Q]: Carolina uses a microscope to view a soil sample taken from her backyard. Which part of the soil would she ONLY be able to see with a microscope?  
 (A) bacteria (B) grass (C) rainwater (D) rocks
[EX A]:
A