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]: What property is the same for each atom of an element?  
 (A) energy (B) mass number (C) atomic number (D) number of neutrons
[A]: C


[Q]: During a biochemical reaction, pyruvate (C3H4O3) is converted into carbon dioxide (CO2) and water (H2O). In what cellular organelle does this biochemical reaction occur?  
 (A) nucleus (B) cytoplasm (C) mitochondria (D) endoplasmic reticulum
[A]: C


[Q]: Indigo buntings are birds that nest in Florida during the summer. Male buntings are bright blue in color while females are a dull brown. How does the dull brown color of the female buntings help the species survive?  
 (A) It helps male birds find a mate. (B) It helps the birds find food more easily. (C) It helps hide the birds while they sit on their nests. (D) It helps the birds find the flock when migrating.
[A]:
C