TASK 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.
PROBLEM: A condition in bees called "colony collapse disorder" occurs when worker bees leave the hive to collect nectar and never return. How would a decline in the bee population most likely affect a farm ecosystem?  
 (A) There would be a decrease in soil thickness. (B) There would be a decline in fruit production. (C) There would be an increase in plant diseases. (D) There would be an increase in insect pest populations.

SOLUTION: B

PROBLEM: Which of the following best describes a role of mushrooms in ecosystems?  
 (A) capturing energy from sunlight (B) consuming living plant material (C) taking energy from animal hosts (D) breaking down dead plant material

SOLUTION: D

PROBLEM: Use The Periodic Table of the Elements and the information below to answer the question. Magnesium metal (Mg) is grayish-white in color and reacts actively with water. Fluorine (F2) is a greenish-yellow gas at room temperature and is a member of the halogen family. These two elements react to produce magnesium fluoride (MgF2), a chemical commonly used in making windows and lenses. How do the elements magnesium (Mg) and fluorine (F2) produce the compound magnesium fluoride (MgF2)?  
 (A) by nuclear connection (B) by physically combining (C) by magnetic connection (D) by chemically combining

SOLUTION:
D