You will be given a definition of a task first, then some input of the task.
In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to protect your infant from flu [title] Get vaccinated. [step] As soon as the seasonal flu vaccine is made available, you and other caregivers should visit your doctor and get vaccinated. By being vaccinated, you'll protect yourself from being infected. <sep> (A) As a result, your chance of infecting your infant will be much lower. Without a flu vaccine, you and your family will be much more vulnerable. (B) [substeps] First, you will need to get vaccinated when you are 15 years old or older. Remember that vaccines do not prevent the flu from occurring in children. (C) All viruses can lead to flu, but there are also vaccinations that prevent a potential recurrence. They're not as important as any other vaccines, though. (D) [substeps] Vaccinations can last for several months. Contact your doctor immediately if you've had the flu in the past, have just become pregnant, or if you have recently given blood.
Output:
A