I'm not so sure, but I think it's C.
I believe the correct term to fill in the blank would be digestive. Four functions of the digestive tract include ingestion, digestion, absorption, and elimination.The digestive tract group of organs that works together to convert the food taken in into energy and nutrients needed by the body.
I believe the answer is <span>D. Examining the different layers of heart tissue</span>
Antigens: Antigens are substances that cause an immune response in the body by identifying substances in or markers on cells. Your body produces antibodies to fight antigens, or harmful substances, and tries to eliminate them.
Antibodies: Antibodies are proteins which belong to a class known as immunoglobulins. They are made up of chains of amino acids joined by peptide bonds.
Cellular immunity: Lymphocytes act against target cell,Acts directly by killing infected cells,Acts indirectly by releasing chemicals that enhance inflammatory response; or activating other lymphocytes or macrophages.
Hope this help!!
