Question

How many major types of blood have scientists discovered?

• A. One: Type "O"
• B. Two: white cells and red cells
• C. Three: white cells, red cells, and plasma
• D. Four: Types A, B, AB and O

Answer 1

The correct option is D Four: Types A, B, AB and O

The ABO blood group was discovered in the first decade of the 1900s by Austrian physician Karl Landsteiner. Through a series of experiments, Landsteiner classified blood into the four well-known types i.e., A, B, AB and O.

So, the correct option is 'Four: Types A, B, AB and O'.