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.

A factory in Japan had been dumping mercury into Minamata Bay. Certain microorganisms in the water were able to change the mercury into a form that the plankton could use. Which most likely happened next?
(A) The organisms built up a resistance to the mercury. (B) The mercury passed through the food chain. (C) The plankton made the mercury safe. (D) The fish would not eat the plankton.
B