Which was not a result of the 1898 discovery of the four blood types?
a. improved blood transfusion safety
b. effective blood preservation solutions developed
c. elements of blood separated via centrifuge
d. all blood types made compatible with each other

The right answer is D. All blood types made compatible with each other

Blood is a liquid tissue that can be easily removed from a healthy individual for transfusion to a sick individual. However, despite an identical cellular composition of this tissue, there is variability, or polymorphism of the various elements of blood between individuals, which makes transfusion impossible between certain groups of people.

People with the same characteristic are said to belong to the same blood group. In general, these characteristics are evidenced by haemagglutination techniques using antibodies or lectins specifically recognizing an epitope. In case of problems, molecular biology can be used. These epitopes, determining various phenotypes, are genetically transmitted.

The discovery of the ABO system, the first of these systems in 1900 by Karl Landsteiner, made it possible to understand why some blood transfusions were successful, while others ended tragically.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.