A new government policy has been developed to avoid many serious cases of influenza. This goal will be accomplished b...

Hi! Here's my understanding of the stimulus, anticipations, and why C makes more sense to me than D. Please let me know where I'm falling short. Conclusion: 2nd part of the last sentence "Every year it will be necessary for all high-risk individuals to receive a vaccine for a different strain of the virus." Anticipations for NP: - The prevalent strain changes yearly (every year, it is a different strain of the vaccine for which high-risk people need to be vaccinated). - Each vaccine protects against 1 strain of influenza. ("Each year's vaccination will protect ONLY AGAINST THE strain of influenza virus deemed most likely to be prevalent that year" + changes yearly). C matches my second NP D matches my first NP, but goes too far. It just needs to change yearly, not that the prevalent strain in one year couldn't have been prevalent in the past (just not in the preceding year). Please let me know where I'm going wrong. I also sense that I made an assumption that vaccines protect individuals for 1 year, is that a fair assumption (though not necessary)? Thanks for your time! Hope to get a response soon. Take care + God bless