TASK DEFINITION: You are given a science question (easy-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.
PROBLEM: Shale is a sedimentary rock that can be metamorphosed into slate by  
 (A) cementation. (B) chemical weathering. (C) sedimentation. (D) increased pressure.

SOLUTION: D

PROBLEM: Which two protein molecules are essential for muscle contraction and relaxation?  
 (A) actin and myosin (B) collagen and tubulin (C) hemoglobin and myoglobin (D) amylase and polymerase

SOLUTION: A

PROBLEM: The discovery of penicillin helped in the  
 (A) treatment of infections. (B) healing of bones. (C) discovery of viruses. (D) search for diseases.

SOLUTION:
A