The clumping of blood from mismatched blood types is a problem for a patient because

The ABO blood group classification is based on antigens on red blood cells and antibodies found in blood plasma.Blood type A has antigen A on the red blood cells and anti - B antibodies in the blood.Blood type B has antigen B on the red blood cells and anti - A antibodies  in the blood.Blood type AB has both antigen A and B on the red blood cells but has no anti-A nor anti - B antibodies in the bloodBlood type O has no antigen on the red blood cells and has both anti -A and anti B antibodies in the blood.

A: rachel carson :

Some of her  assignments would be creation of drugs. she is a medical chemist after all so she'd need to have the necessary knowledge to make medicine which can later be sold in a pharmacy