1. The primary purpose of the passage is to
The first paragraph of the passage explains the changes in the influenza virus as it mutates and hence the requirement of frequent vaccinations. The second paragraph talks about the steps being taken by researchers to develop a one-time vaccination for flu.
(A) explain the process by which the influenza virus mutates quickly, thus making the development of a single vaccination impossible The passage does not explain the steps of mutation, nor does it say that the development of a single vaccine is "impossible. Eliminate.
(B) identify the action of hemagglutinin within the influenza virus that causes the virus to evolve rapidly The passage only states that the hemagglutinin evolves, whether rapidly or not we do not know. It also does not specify the specific action by which it evolves. Eliminate.
(C) compare and contrast the influenza virus with the viruses that cause polio, measles, mumps, and other virus-borne diseases There is only one sentence (the first, maybe the second as well) which contrasts the flu virus with those of other diseases - this cannot be the "primary purpose" of the passage. Eliminate.
(D) discuss the reason influenza vaccinations are administered annually and recent innovations in research that may address this anomaly Correct. Consistent with our thinking above.
(E) describe the mechanism of antigenic drift and how this process affects the human immune system The passage does not describe the "process" or antigenic drift. Eliminate.
2. It can be inferred from the passage that the author believes which of the following to be true about a vaccine that could provide permanent protection against influenza with a single immunization protocol?
On this topic, the author's opinion is given by: "While much work remains to be done, a vaccine targeting one of these may be the key to a one-time immunization protocol that would provide efficacious protection against most influenza strains."
(A) Research into such a vaccine is promising, and the vaccine will be available soon if tests are completed successfully. The author does not state this. Eliminate.
(B) The vaccine could affect neuraminidase or other areas of the virus that do not mutate rapidly. Correct. Consistent with above.
(C) Such a vaccine cannot be effective because hemagglutinin antigens evolve too quickly. The author does not state this. Eliminate.
(D) The vaccine will most likely target hemagglutinin antigens because their rapid mutation makes them susceptible to the defenses of the human immune system. The author, in fact, states that such a vaccine should target neuraminidase and not hemagglutinin. Eliminate.
(E) The vaccine will have a similar mechanism to that of the vaccines now administered for polio, measles, mumps, and other virus-borne diseases. The author does not state this. Eliminate.
3. According to the passage, each of the following is true of the influenza virus EXCEPT:
(A) The rapid evolution of hemagglutinin on the surface of the virus can prevent the human immune system from recognizing and attacking the virus. This is true ("As hemagglutinin is copied, it is not replicated exactly, so the human immune system does not recognize the mutation as the same protein it has encountered before and does not inaugurate the immune response"). Eliminate.
(B) Some of the surface proteins on the influenza virus have different functions. This is true. Different functions are identified for the surface proteins neuraminidase ("..assists in the release of new viruses from the cell..") and hemagglutinin ("..involved in the invasion of a cell .."). Eliminate.
(C) The antigenic drift of the influenza virus means that a vaccine against influenza must change frequently. This is true ("..the known strains of influenza are recognized and effectively combated, but, unchallenged by the immune system, mutated viruses are able to reproduce freely and, thus, form a new strain of influenza" and "vaccinations combating the influenza virus must be administered annually...the reason for this striking difference is the ability of the influenza virus to evolve quickly"). Eliminate.
(D) Annual immunization is not always effective protection against the influenza virus. This is true ("..vaccinations combating the influenza virus must be administered annually, and even then they may not be fully successful in preventing illness.."). Eliminate.
(E) The influenza virus is remarkable in its ability to mutate more rapidly than any other known virus. Correct. The passage does not state anything about the ability of the flu virus to mutate compared to other viruses.
Hope this helps.