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:
Which of these objects is translucent?  
 (A) A student's notebook (B) A mirror on the bus (C) A brick wall of the school (D) A student's sunglass lenses
answer:
D


question:
Which layer of Earth is the source of lava that erupts from volcanoes?  
 (A) asthenosphere (B) inner core (C) outer core (D) lithosphere
answer:
A


question:
What change has taken place in the following? K -> K^+  
 (A) loss of a proton (B) gain of a proton (C) loss of an electron (D) gain of an electron
answer:

C