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.
--------
Question: The molecule ATP is composed of elements commonly found in organic molecules. Which of the following is one of these elements?  
 (A) aluminum (B) calcium (C) phosphorus (D) tin

Answer: C


Question: Which best describes a scientific theory?  
 (A) It is still being tested. (B) It is true, once written. (C) It is different for each continent. (D) It is determined in a court of law.

Answer: A


Question: Lightning from a thunderstorm strikes a 21 tree that falls to the forest floor and dies. During the next few years the dead tree undergoes many changes. What organisms are most likely responsible for the biological and chemical changes to the tree?  
 (A) consumers (B) decomposers (C) predators (D) producers

Answer:
B