Answer;
-All blood types made compatible with each other
Explanation;
-In 1898, it was discovered that inherited differences in people’s red cells were the cause of many of the incompatibilities found with transfusions.
-During World War I, when human blood was needed for transfusions for wounded soldiers, studies began of how to preserve and transport blood and four blood types were identified.
They felt that the war could be risky <span />
It's where two or more cells involves.
like magnets