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]: What is the downward movement of water through pores and other spaces in soil due to the force of gravity?  
 (A) percolation (B) evaporation (C) precipitation (D) condensation
[A]: A


[Q]: Why should plants be included in investigations about the water cycle?  
 (A) Plants speed up the water cycle by removing carbon from the air. (B) Plants start the water cycle when they make water in photosynthesis. (C) Plants are part of the water cycle through the process of transpiration. (D) Plants stop the water cycle because they absorb it and stop the flow to streams.
[A]: C


[Q]: When chemicals in the atmosphere dissolve in water droplets, they precipitate with the water and pollute water reservoirs on Earth. The pollutants enter the food chain when aquatic organisms absorb them. Which of these pollutants eventually contaminates fish after coal is burned?  
 (A) lead (B) arsenic (C) mercury (D) aluminum
[A]:
C