Part 1. Definition
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.
Part 2. Example
Which part of a bicycle BEST moves in a circle? 
 (A) Seat (B) Frame (C) Foot pedal (D) Kickstand
Answer: C
Explanation: Seat, frame and Kickstand are static parts of the bicycle, even when bicycle moves. Foot pedal moves in a circle as bicycle moves.
Part 3. Exercise
Scientists go to a lake once a month to take samples of water. They are most likely studying the  
 (A) number of fish. (B) depth of the lake. (C) quality of the water. (D) speed of the water.
Answer:
C