TASK DEFINITION: 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.
PROBLEM: Which unit of measurement describes an object's length?  
 (A) meter (B) kilogram (C) liter (D) degree

SOLUTION: A

PROBLEM: Which illustrates the correct order of relationships in organisms?  
 (A) tissue -> organ system -> organ -> cell (B) organ -> cell -> organ system -> tissue (C) cell -> tissue -> organ -> organ system (D) organ system -> organ -> cell -> tissue

SOLUTION: C

PROBLEM: What happens to water when it boils?  
 (A) It changes color. (B) It becomes heavier. (C) It changes into water vapor. (D) It stops bubbling.

SOLUTION:
C