instruction:
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.
question:
The respiratory system cannot deliver oxygen to the cells of the body, nor can it remove carbon dioxide, without which two body systems?  
 (A) muscular and nervous (B) digestive and muscular (C) cardiovascular and nervous (D) cardiovascular and muscular
answer:
D


question:
Clay is watching the weather to prepare for a trip to the beach tomorrow. The forecast predicts that a low-pressure system will move in overnight. Which type of weather can Clay most likely expect in the morning?  
 (A) foggy (B) sunny (C) clear and colder (D) cloudy and rainy
answer:
D


question:
Planets orbit  
 (A) Earth. (B) the Moon. (C) the galaxy. (D) the Sun.
answer:

D