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

A student conducts an investigation. In order to make a valid conclusion, she must  
 (A) have a testable hypothesis. (B) place the data in a graph. (C) use the best technology. (D) test multiple variables.
A

Use the information below to answer the question. Cotton is a plant product used to make fabric. Cotton is made of cellulose, a fiber not digestible by humans. Cellulose is composed of many sugar molecules bonded together into long chains. Each sugar molecule contains carbon, hydrogen, and oxygen atoms. When cotton fabric is washed, wrinkles often form. The clothing industry uses chemicals to manufacture some cotton fabrics that are wrinkle-free. Dyes are also added to color the cellulose fibers in cotton. A feature that is common to both cellulose and sugar is that both are  
 (A) magnetic (B) elements (C) compounds (D) soluble in water

C