Answer:
antigen is any molecule, molecular structure, foreign particulate matter that triggers an immune response. antigens are not antibodies.
Step-by-step explanation:
an antigen is considered a type of molecule that is foreign to the body that it is found in. this stimulates the immune system and antibodies are formed. this is called antigen- antibody reaction.
for example: if you have an A antigen in your RBC then you have anti A (beta) antibodies in your blood serum. this results in having no agglutination.