Answer:
a.
Explanation:
It decreases from the aorta to the vena cava.
Just like the comment above that’s rig jt
A primary reason for needing a new vaccine for influenza each year is that there could be mutation of surface proteins leading to a new outbreak
<h3>What is antigenic drift?</h3>
Antigenic drift is a phenomenon that causes small changes or mutations in the genes of influenza viruses leading to changes in their surface proteins of the virus, which are HA (hemagglutinin) and NA (neuraminidase).
For this reason, new influenza vaccines are produced yearly to alter the effects that may emerge as a result.
Thus, a primary reason for needing a new vaccine for influenza each year is that there could be mutation of surface proteins leading to a new outbreak
Learn more about influenza here:
brainly.com/question/12975693
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