Respuesta :
					                   It helps the immune system recognize the pathogen and be more aware about the pathogen for a certain period of time. Therefore if a LIVING version of that pathogen were to enter the immune system, the immune system would be able to react to the pathogen quicker.
					                
					                
					             
					                   D. A vaccine causes the secretion of antibodies which remain in blood and fight the pathogen at the time of an infection.
					                
					                
					              
			                  