Detailed Instructions: 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.
Q: Students studying membranes conducted an experiment using labeled paper cups filled with varying concentrations of red food coloring. After the experiment, the cups were empty and stained. What should be done with used cups?
(A) reuse the cups (B) dispose of the cups (C) recycle the cups (D) relabel the cups
A:
C