What is the source of the oxygen released into the air as a product of photosynthesis?
a. chlorophyll
b. carbon dioxide only
c. water only
d. both water and carbon dioxide

Vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a.) antibody, antibiotic b.) antigen, antibody c.)antibiotic, antibody d.)antibody, antigen