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:
What is the most common element in a star such as the Sun?  
 (A) helium (B) oxygen (C) nitrogen (D) hydrogen
answer:
D


question:
One type of cold remedy is an effervescent tablet that breaks down in water. When the tablet is placed in water, it forms gas bubbles. In this example, the formation of a gas  
 (A) is a physical property. (B) occurs when adding water to acid. (C) is a sign of a chemical change. (D) occurs when the water boils.
answer:
C


question:
Which apparatus would not be needed during an animal dissection?  
 (A) gloves (B) goggles (C) lab smock (D) safety shower
answer:

D