I'd go with A, if I were you.
Answer:
by mimicking disease agents and stimulating the immune system to build up defenses against them.
Explanation:
Gas chromatography (GC) is a method of separating mixed compounds.
The separation will depend on each compound's retention time. Compounds with
higher molecular weights will elute out slower than those with lower molecular
weight. This is due to their difference in boiling points. The larger the
structure, the higher the boiling point.
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Administer varicella vaccine to the health 6-year old child (who does not have evidence of immunity to varicella) was exposed to a confirmed case of varicella 2 days ago.
Explanation:
It is seen that if a child receives varicella vaccine between 3 to 5 days of exposure, he is safe as disease will not appear in him and would be saved for future infections.
Varicella vaccine is given for prevention against small pox. It is expected once immunised with varicella body will produce antibodies for a span of twenty years or more.