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.

Compost piles have many parts, such as leaves, moisture, vegetables, and microorganisms. Which part of a compost pile breaks down materials and adds nutrients to the soil?  
 (A) leaves (B) moisture (C) vegetables (D) microorganisms
D

Andre learned that plants survive through a process called photosynthesis. Which substance do plants produce during photosynthesis?  
 (A) minerals (B) nitrogen (C) soil (D) sugar
D

A wetland was drained to build a mall. Two years later, there were no more toads in that area. Why did the toads disappear?  
 (A) The toads were destroyed by the construction equipment. (B) The toads died because toads cannot breathe out of water. (C) The toads were frightened and went into the woods. (D) The toads go their food from the wetland ecosystem.

D