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.

Ex Input:
A group of students observed the formation of bubbles when water boiled. What happened to matter because of the physical change to the water?  
 (A) New matter was created in the bubbles. (B) Old matter was destroyed as the water turned to gas. (C) Matter was conserved when it changed form. (D) The composition of the matter changed.

Ex Output:
C


Ex Input:
Which of these reduces the need for people to use nonrenewable resources?  
 (A) recycling paper products (B) watering the lawn once a week (C) designing cars that are fuel efficient (D) using coal to generate electricity

Ex Output:
C


Ex Input:
Which of the following does not affect the strength of an electromagnet?  
 (A) number of times the wire is looped around the core (B) size of the object being attracted by the core (C) type of material in the core (D) amount of material in the core

Ex Output:

B


