Given the task definition and input, reply with output. 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.

Katie has a mixture of iron filings and sand. She wants to separate them. How can she do this?
(A) Shake the mixture, and the iron filings will rise to the surface. (B) Add water to the mixture, and the sand will dissolve in the water. (C) Put the mixture through a sieve, and the sand will remain in the sieve. (D) Pass a magnet over the mixture, and the magnet will attract the iron fillings.
D