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.

[EX Q]: Helen is preparing a presentation about objects in the solar system. She includes facts about the order of the planets and their distances from the Sun. Which statement could she include in an accurate presentation?  
 (A) Mars is closer to the Sun than Earth. (B) Neptune is one light-year from the Sun. (C) Jupiter is farther from the Sun than Uranus. (D) Earth is one astronomical unit from the Sun.
[EX A]: D

[EX Q]: Earth is about 81 times more massive than the Moon. How will the mass and weight of a rocket on the Moon compare to its mass and weight on Earth?  
 (A) The mass and weight will be less on the Moon. (B) The mass and weight will be greater on the Moon. (C) The mass will be the same, but its weight will be less on the Moon. (D) The mass will be the same, but its weight will be greater on the Moon.
[EX A]: C

[EX Q]: The number of neutrons in an atom is found by subtracting  
 (A) atomic number from mass number. (B) mass number from atomic number. (C) atomic number from electron number. (D) isotope number from electron number.
[EX A]:
A