听力原文： The death rate from influenza rose markedly in the 1990's, federal scientists re

ported. The explanation, they said, is that a greater proportion of the population is elderly and thus particularly susceptible to flu. There was an average of 36,000 flu deaths a year in the 1990's as compared to 20,000 a year in previous decades, the investigators, from the Centers for Disease Control and Prevention, reported in the Journal of the American Medical Association. Ninety percent of influenza deaths were in people 65 and older, said Dr. Keiji Fukuda, the principal researcher for the study. But Dr. Fukuda and his colleagues reported that the virus was especially deadly in people over 85, who might be up to 32 times more likely than those 65 to 69 to die from a flu infection.

The researchers also concluded that there were large numbers of deaths among the elderly from another virus, respiratory syncytial virus, known as R. S. V. As many as 78 percent of the 11,000 people who died from R. S. V. each year were 65 and older, the researchers concluded.

In an editorial accompanying the paper, Dr. David M. Morens of the National Institute of Allergy and Infectious Diseases, said that many people who were particularly vulnerable to influenza did not get flu vaccines, the only method of preventing the disease. Many mistakenly believe that the vaccine, which is made from a killed virus, can give them the flu. Over the last few years, Dr. Fukuda said, just 65 percent to 67 percent of people 65 and older were immunized. Even when they do get the vaccine, he added, it is less effective in the elderly than it is in younger people. And there is no vaccine to protect against R. S. V. Dr; Morens was not optimistic about the immediate future. The best hope, he said, is for improved flu vaccines and a vaccine for R. S.V. But for now, he said, doctors must do a better job of persuading older people to be vaccinated.

How many flu deaths a year in the 1990's？

A．20,000

B．26,000

C．30,000

D．36,000