A、Doctor of Medicine. B、Medical Department. C、Managing Director. D、Manufacturing Department. C由短文中提到的the Managing Director，or MD

As Managing Director of our company I’ve been asked to say a few words to you today about the way the company is organized. At the top above me, there’s the Board of Directors. Their job is to administrate the company, make general policies, and so on. There are two kinds of Directors, actually. One kind is what we call non-executive Directors, which means that they are standing in various parts of the business world and are in a position to help the company to succeed. They only appear when there are meetings of the Board, and some of them are on the boards of other companies at the same time. But the second lot of Directors — the Executive Directors — are full-time employees of the company. Most of them are managers of our various departments.
    The absolute head of the company, of course, is the Chairman of the Board. He is appointed by the Board, and his job is to take the chair at meetings of the shareholders and the Board of Directors, and to represent the company’s interests at outside functions. He does not take much part in the running of the business. He leaves me to get on with the job. Mind you, not all chairmen are like that. Our last one was a real pain, always wanted everything done in his own way and he kept on interfering.
    Then there’s me, the Managing Director, or MD for short — as long as you don’t think I’m a Doctor of Medicine. Now, my job is to coordinate the policies decided by the Directors and see that they are carried out. I do this through the various managers of departments.
Questions 16 to 18 are based on the passage you have just heard.
16. What is the main topic of the talk?
17. Who is responsible for chairing the meetings of the shareholders?
18. What is MD short for?