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: If an atom has two protons and three electrons, then the atom is  
 (A) positively charged. (B) negatively charged. (C) radioactive. (D) neutral.

Answer: B


Question: Which activity is an example of a good health habit?  
 (A) riding a bicycle without a helmet (B) smoking cigarettes (C) wearing a hat while in the Sun (D) eating with dirty hands

Answer: C


Question: A student is using descriptions to classify organisms. One organism is described as having sense organs to detect heat, laying eggs to reproduce, using venom for protection, and having the ability to change body temperature with its surroundings. How would the student classify this organism?  
 (A) bacteria (B) mammal (C) reptile (D) bird

Answer:
C