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: Which action involving a pulley system requires the least amount of force?
(A) using several pulleys together instead of a single pulley (B) using a fixed pulley instead of a moveable pulley (C) pulling a long rope instead of a short rope (D) pulling a rope up instead of down

SOLUTION: A

PROBLEM: Earth is composed of layers of material with different properties. Which of the following is most likely to be in constant motion?
(A) core (B) mantle (C) oceanic crust (D) continental crust

SOLUTION: B

PROBLEM: When two objects are touching, heat is transferred from the warmer object to the cooler one by
(A) radiation. (B) convection. (C) conduction. (D) insulation.

SOLUTION:
C