TASK DEFINITION: You are given a science question (hard-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: One example of a living thing is  
 (A) air (B) water (C) a rock (D) a worm

SOLUTION: D

PROBLEM: In which way is any single observation of wind speed best described?  
 (A) It is an indication of a future weather condition. (B) It is an indication of the amount of humidity. (C) It is an indication of weather at a specific time. (D) It is an indication of the existing climate.

SOLUTION: C

PROBLEM: A student mixed salt and sugar. Which statement describes the physical properties of salt and sugar after they were mixed?  
 (A) The sugar dissolved the salt. (B) The salt and sugar changed color. (C) The sugar and the salt were unchanged. (D) The salt and sugar formed a new material.

SOLUTION:
C