TASK DEFINITION: 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.
PROBLEM: What property is the same for each atom of an element?  
 (A) energy (B) mass number (C) atomic number (D) number of neutrons

SOLUTION: C

PROBLEM: What type of force keeps the planets orbiting the Sun?  
 (A) gravitational (B) magnetic (C) electrical (D) nuclear

SOLUTION: A

PROBLEM: During which stage of an insect's life cycle does the female lay eggs?  
 (A) nymph (B) larva (C) pupa (D) adult

SOLUTION:
D