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.

A student placed a small chip of limestone into a hydrochloric acid solution, and carbon dioxide gas was released. The carbon dioxide provided evidence that   
 (A) only a physical change occurred. (B) a chemical change occurred. (C) only a loss of mass occurred. (D) the formation of an element occurred.
B

Which describes a specific characteristic necessary for survival in the desert?  
 (A) conserving water (B) hiding from predators (C) hibernating for long periods (D) producing many offspring
A

A student compares a plant cell to an animal cell. Which structure will the student find ONLY in the plant cell?  
 (A) chloroplast (B) nucleus (C) mitochondrion (D) cytoplasm

A