Answer
$8$ blood types.
Work Step by Step
There are 4 types of blood groups as A, B, AB, and O. In addition to this, the blood is also classified as Rh+ and Rh- blood. So, based on the counting principle, there will be 2 x 4 = 8 blood types as
A+
A-
B+
B-
AB+
AB-
O+
O-
