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:
Which human organ system eliminates liquid and gaseous wastes from the body?  
 (A) circulatory (B) endocrine (C) excretory (D) reproductive
answer:
C


question:
When manned space exploration began, NASA used the gravity assist concept so that spacecraft could conserve fuel. Which statement explains why the gravity assist concept was useful for spacecraft to successfully travel and return to Earth?  
 (A) It gave spacecraft a timed trajectory. (B) It ensured spacecraft would return home safely. (C) It was helpful in planning spacecraft trajectories. (D) It ensured spacecraft would avoid being pulled into the sun.
answer:
C


question:
A loaf of bread is baking in a pan in a 350° F oven. What would cause a burn to a hand the quickest because of its low specific heat?  
 (A) the metal pan (B) the air in the oven (C) the surface of the bread (D) the outside of the oven door
answer:

A