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:
Manuel wants an area in the yard to wash the dog without making mud puddles. He wants to put something on the ground that water passes through easily. Which of these materials would be the best for him to use?  
 (A) clay (B) plastic (C) soil (D) pebbles

Ex Output:
D


Ex Input:
Which of these best describes a change that is physical?  
 (A) yarn being knitted into a sweater (B) the engine from a tractor being started (C) the metal on a bicycle forming rust (D) grass capturing the energy from sunlight

Ex Output:
A


Ex Input:
Which process is included in the formation of both metamorphic and sedimentary rock?  
 (A) heating (B) recrystallization (C) compaction (D) weathering

Ex Output:

C