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: Which example best illustrates an action-at-a-distance force?  
 (A) lifting a box (B) an apple falling (C) pulling a nail out of wood (D) a car moving along a flat surface

SOLUTION: B

PROBLEM: The classification of some organisms has changed. Which new process is used to reclassify organisms?  
 (A) Organisms are now given Latin-based scientific names. (B) Structures are now examined at the molecular level. (C) Organisms are now divided into three kingdoms. (D) Structures are now used to classify organisms.

SOLUTION: B

PROBLEM: What do cells break down to produce energy?  
 (A) food (B) water (C) chlorophyll (D) carbon dioxide

SOLUTION:
A