閱讀測驗一 (第 41-45 題)       When the flu season begins during the late fall of each year, youmay hear doctors or health officials remind the public to get their annualflu shots. However, many people have asked, “If the vaccine iseffective, then why do people need a new one each year?”       According to medical experts, people need a yearly flu shotbecause the virus that causes the flu is constantly evolving. The virus,known as influenza, can cause a wide range of uncomfortablesymptoms, from a mild sore throat to severe muscle pains. For somedemographics, such as the elderly or the overweight, getting sick withthe flu can be deadly.       Since the outer structure of the influenza virus changes all thetime, epidemiologists must work hard to develop new vaccines based onnew strains of the virus in order for them to be effective. At influenzasurveillance centers around the world, new strains of the virus arereported and analyzed each year. Around February, the World HealthOrganization (WHO) decides which of these strains are most likely to beprominent in the coming year. Scientists then get to work to produce anew vaccine before the next flu season arrives. It’s also important toremember that the body’s immune system is constantly developing aswell； it’s not just the influenza virus that is changing. That means avaccine that might have been effective last year is likely to be uselessafter 12 months. That’s why experts recommend getting a new flu shotyearly to protect yourself and others.       Remember: the vaccines not only alleviate the worst symptomsof the virus but also help reduce transmission of the viral diseasethroughout the population.
【題組】41, What is the purpose of this article?
(A) To illustrate how deadly influenza is
(B) To describe how hard it is to develop a new vaccine
(C) To explain why people need annual flu shots
(D) To praise the contribution of the World Health Organization