An experimental treatment that causes AIDS patients to develop a dangerously high fever has shown promise as a way of prolonging and improving the patients' life.Called the Biologic-HT System, the new treatment lets doctors extract the blood of a patient and heat it before circulating it back into the body. The heated blood causes the patient's body temperature to rise above 42 degrees Celsius. In people with AIDS, that increase in temperature kills some heat-sensitive HIV, the virus, most doctors say, causes AIDS. Heating the blood of AIDS patients has been tried before, say doctors. But during previous attempts, the treatment induced deadly chemical changes in the blood. The Biologic-HT System prevents those changes from happening, allowing the heat to kill viruses with few ill side effects. The new heat treatment cannot be considered a cure for Aids, says president of the company that makes the system. He says the treatment doesn't kill all traces of the virus. However, it kills enough virus particles to give a patient's immune system a reprieve in its deadly duel with HIV. Tests of the Biologic-HT treatment began on 36 patients earlier this year. The treatment takes about four hours, and the patient normally feels well enough to leave the hospital or clinic the following morning. So far, the patients who have had the treatment say they feel better and have developed no new opportunistic infections--disease that strike people with damaged immune systems. The patients also have experienced about a 50 percent increase in the number of T cells in their bodies. T cells are key disease-fighting cells of the immune system and the main target of HIV. The blood of the patient  _  .
is heated with a single injection is heated by being circulated at a higher rate is taken out from the body and then circulated through a heating system. is taken out from the body, heated outside and then put back into the body.
Question: An experimental treatment that causes AIDS patients to develop a dangerously high fever has shown promise as a way of prolonging and improving the patients' life.Called the Biologic-HT System, the new treatment lets doctors extract the blood of a patient and heat it before circulating it back into the body. The heated blood causes the patient's body temperature to rise above 42 degrees Celsius. In people with AIDS, that increase in temperature kills some heat-sensitive HIV, the virus, most doctors say, causes AIDS. Heating the blood of AIDS patients has been tried before, say doctors. But during previous attempts, the treatment induced deadly chemical changes in the blood. The Biologic-HT System prevents those changes from happening, allowing the heat to kill viruses with few ill side effects. The new heat treatment cannot be considered a cure for Aids, says president of the company that makes the system. He says the treatment doesn't kill all traces of the virus. However, it kills enough virus particles to give a patient's immune system a reprieve in its deadly duel with HIV. Tests of the Biologic-HT treatment began on 36 patients earlier this year. The treatment takes about four hours, and the patient normally feels well enough to leave the hospital or clinic the following morning. So far, the patients who have had the treatment say they feel better and have developed no new opportunistic infections--disease that strike people with damaged immune systems. The patients also have experienced about a 50 percent increase in the number of T cells in their bodies. T cells are key disease-fighting cells of the immune system and the main target of HIV. The blood of the patient  _  .
A. is heated with a single injection
B. is heated by being circulated at a higher rate
C. is taken out from the body and then circulated through a heating system.
D. is taken out from the body, heated outside and then put back into the body.
Answer: