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.

The prairie grass ecosystem once had a deep layer of topsoil which was protected by the grasses that covered it. Removal of these grasses for farmland is causing the soil to be eroded mainly by  
 (A) wind and rain. (B) animal movement. (C) crops grown in the soil. (D) increased temperatures.
A

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
D

Which is most likely a direct cause of an ear infection?  
 (A) loud noises (B) foreign bacteria (C) wearing tight hats (D) dirty ear canals

B