Final answer:
When exposed to a common cold virus, it is referred to as an antigen. Plasma cells produced by B cells secrete antibodies to fight off viral infections.
Step-by-step explanation:
The subject of the question is Biology.
When you are exposed to a common cold virus through contact with someone who is sick, the virus is considered an antigen. Antigens are substances that can stimulate an immune response in the body.
Plasma cells are produced by B cells in response to an antigen, and they secrete antibodies which can help fight off the viral infection. Antibodies are proteins that specifically bind to antigens and neutralize them.
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