A. <span>Exposure to an antigen
Exposure to viruses and antigens led to the foundation of modern vaccination. Vaccination introduces an antigenic material that helps the ability of the immune system to adapt a specific pathogen, therefore leading to a long-term immunity.</span>
The neurotransmitter in the body
which prepares it for "fight or flight" reaction is EPINEPHRINE. The
level of Epinephrine is remarkably high in patients who have anxiety-related
disorders. Also known as adrenalin or adrenaline, epinephrine is a hormone and at the same time a neurotransmitter; it is also used as medication.
Answer: Up
Explanation: when an electron goes up it produces more energy which makes light. :)
D is the correct answer since all others are highly unlikely.
It looks correct to me. Good job
