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:
The best example of balanced forces is a  
 (A) car increasing speed. (B) bus parked in a garage. (C) ball kicked along a flat surface. (D) roller coaster slowing down on an incline.

Ex Output:
B


Ex Input:
The students in a class are making a scale model. They need a material that they can easily bend into a circle. Which of the following objects is best for the students to use?  
 (A) copper wire (B) glass rod (C) lead pipe (D) wooden stick

Ex Output:
A


Ex Input:
A plant that needs well-drained soil would grow best in soil made mostly of  
 (A) silt. (B) clay. (C) sand. (D) humus.

Ex Output:

C