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.

Scientists working for a company are testing a new medicine that they think will help heal damaged tissue. In which part of the company are the scientists working?
(A) distribution (B) mass marketing (C) public relations (D) research
D