Karl landsteiner placed animal blood in human blood and discovered that the blood clumped. which did his creativity lead to?
understanding the process of blood clotting
understanding the formation of blood cells
understanding the function of antibodies
understanding a, b, ab, and o blood groups

Karl Landsteiner understood the different blood groups A, B, AB, and O. He was a biologist and physician that distinguished these main blood groups in the 1900. He was also the man behind the discovery of polio virus in 1909 and had received the Nobel Prize in Physiology in the year 1930. Today he is currently recognized as the father of transfusion medicine. 

d) understanding A, B, AB, and O blood groups

Explanation:

its says so e 2020

B: Get closer together

Explanation:

if you look at a globe the lines of longitude get closer together as you go away from the equator