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.

[EX 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
[EX A]: C

[EX Q]: Which of the following happens in our solar system?  
 (A) Earth revolves around the sun once per day. (B) The moon revolves around Earth once per day. (C) Earth revolves around the sun once per year. (D) The moon revolves around Earth once per year.
[EX A]: C

[EX Q]: The density of 200 mL of water was determined, and then 20 grams of sugar was dissolved in the water. The student determined the density of the sugar-water solution and recorded the collected data in a table. The sugar in this investigation is  
 (A) the solute. (B) undergoing chemical change. (C) the solvent. (D) changing from a solid to a gas.
[EX A]:
A