In the past 100 years the major causes of death have shifted from to

The answer is from infectious diseases to chronic. The term chronic is often functional when the sequence of the disease lasts for more than three months. Chronic diseases are the disease that is determined or otherwise long-lasting in its effects or a disease that comes with time. While Infectious diseases are illnesses caused by organisms. Some infectious diseases can be handed from person to person. Some infectious disease is — such as bacteria, viruses, fungi or parasites. 

answer; ///(b) it is composed of four protein chains and four heme groups;