【正确答案】 A

【答案解析】[解析] There've been several influential studies in pain management. Some of the most interesting of these study endorphins, the body's own natural painkillers. For example, we now know that exercise stimulates the productior, of endorphins. Lack of exercise, on the other hand, not only shuts down endorphin production, but can also lead to muscle deterioration. This is why you see a lot of pain specialists prescribing exercise for patients with chronic pain. Another interesting area involves the power of the placebo effect. We've known for some time that a sugar pill or other inactive placebo can sometimes make a sick person feel better. Somehow, the power of suggestion ... or faith in the doctor, or the drug ... will start a process of healing. We now think a neurochemical component--what may actually happen is the placebo effect allows some people to sort of tap into the supply of endorphins in their own brains. What is the lecture mainly about? The speaker mainly discusses research in pain management. He says: There've been several influential studies in pain management. He then gives examples of research studies.