Question

lo 2.2. how many main blood types are there? 4 9 3 8 5

Explanation:

The main blood types are determined by the ABO and Rh systems. The ABO system has four types (A, B, AB, O), and when combined with the Rh factor (positive or negative), there are 8 main blood types (A+, A-, B+, B-, AB+, AB-, O+, O-).

Answer:

8