Which is a true statement about vaccines?

a.
vaccines can protect against the spread of specific diseases.

b.
vaccines cause the nervous system to destroy specific germs.

c.
vaccines usually increase the spread of specific diseases.

d.
all of the above

relationship between pressure and air volume and led to the understanding of how respiration works; i believe this is the correct answer ; /// good luck

the more fit you are, the faster the recovery. your heart rate drops most sharply in the first minute after you stop exercising; it should then fall about 20 beats a minute—a drop of less than 12 beats a minute is considered abnormal. this “recovery heart rate” is measured as part of an exercise stress test.

i think the answer is c

hope this