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]: Which characteristic best identifies a pure substance?  
 (A) shape (B) texture (C) melting point (D) state of matter
[EX A]: C

[EX Q]: Patricia and her classmates are visiting different rocky areas in the city. They want to know what kind of rocks can be found in each area. If the investigation is done correctly, what will Patricia and her classmates do each time they visit an area?  
 (A) draw the rock shapes (B) count the rock numbers (C) record the rock types and locations (D) measure the rock masses and lengths
[EX A]: C

[EX Q]: The purpose of thorns on a plant is most likely to  
 (A) help the plant to get moisture. (B) anchor the plant in the ground. (C) protect the plant from harm. (D) support the stems and branches.
[EX A]:
C