What is the author’s purpose in the article what is a vaccine? A. to encourage people to get as many vaccines as they can
B. to explain how vaccines help the immune system
C. to warn people about the dangers of not taking vaccines
D. to emphasize the incredible abilities of the immune system

Write an explanation for how to perform some kind of physical activity, such as riding a bike or playing a sport. the explanation should be geared toward someone who has never performed the activity. be sure to explain the steps in the process clearly, organize your ideas appropriately, use text features