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:
As part of a study, a scientist observed a number of different molecular changes in matter. Which of the following observations provides evidence of a physical change?  
 (A) using heat to burn a log in a fireplace (B) using light to produce sugar in plants (C) a cake that was baked from many ingredients (D) a bottle that was broken into many small pieces

Ex Output:
D


Ex Input:
A pot is touching the flame of a gas stove, and the substance in the pot is heating up due to the contact. This is an example of which type of energy transfer?  
 (A) radiation (B) convection (C) conduction (D) vaporization

Ex Output:
C


Ex Input:
Michael has a pencil case made of pine wood. The surface of the pencil case scratches and dents easily. He wants to make a new pencil case that will not scratch or dent easily. Which of the following should Michael do to make a new pencil case that will not scratch or dent easily?  
 (A) make the pencil case a different size (B) use a different material to make the pencil case (C) make the pencil case from another piece of pine wood (D) use a thicker piece of pine wood to make the pencil case

Ex Output:

B