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]: A student wants to organize a group of animals into two categories based on observable external features. Which display will most appropriately show the two categories of animals?     
 (A) a timeline (B) a pie chart (C) a data table (D) a line graph
[A]: C


[Q]: A scientist combines oxygen and hydrogen to form water. This combination illustrates that water is  
 (A) an atom. (B) an element. (C) a mixture. (D) a compound.
[A]: D


[Q]: Earth's core is primarily composed of which of the following materials?  
 (A) basalt (B) iron (C) magma (D) quartz
[A]:
B