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.

[Q]: The cells of a plant help the plant maintain its life functions. What part of a plant cell has the function of producing sugar in the presence of sunlight?  
 (A) chloroplast (B) cytoplasm (C) mitochondria (D) nucleus
[A]: A


[Q]: Which describes a material that is not a food?  
 (A) It stores energy but not nutrients. (B) It does not store energy or nutrients. (C) It stores energy and nutrients. (D) It does not store energy but stores nutrients.
[A]: B


[Q]: Which organ is the site of gas exchange between the body and the environment?  
 (A) spleen (B) liver (C) lungs (D) pancreas
[A]:
C