A specific immune response begins when a white blood celomes in contact with an antigen (any substance that the immune
system does not recognize as part of the body). What external factor typically triggers a specific immune response?
ОА. an invasion of a microorganism from the external environment
OB.
a fluctuation of the external air pressure
OC. a large release of adrenalin by the endocrine system
OD. a change in the external temperature