The process by which a dead or disabled pathogen (or proteins from that pathogen) is introduced into the body so that an immune response results without actual infection.
a. autoimmunity
b. an allergic reaction
c. immunity
d. vaccination

D. Vaccination 

A vaccination is a dead or weakened virus that is put into your body so that your body can kill the weakened pathogen easily so that if the actual strong pathogens enter your body your system has already had a "practice round" and therefore knows how to kill the pathogens.

Neurotransmitters are messengers responsible for communication between neurons. they are released from synaptic vesicles and are received by receptors.  the communication is referred to as neurotransmission. the following statement is true about neurotransmitters: a. they're stored in synaptic vesicles in the axon.