instruction:
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.
question:
Electron transport in mitochondria results in a chemiosmotic gradient of which particle across the mitochondrial membrane?  
 (A) ADP (B) ATP (C) protons (D) neutrons
answer:
C


question:
On a cold, cloudy day, the local weather forecaster predicts that a high-pressure system will be moving into the area in the next 24 hours. Which weather conditions will this system most likely bring to the area?  
 (A) stormy (B) sunny (C) snowy (D) hot
answer:
B


question:
Planets remain in orbit around the Sun because of  
 (A) gravity. (B) friction. (C) solar energy. (D) centrifugal force.
answer:

A