Roughly how many American have type o+ blood?

In the U.S., 38% of the population have O-positive blood, making it the most common blood type.

Explanation:

According to the American Red Cross, the following statistics show the most common blood types in the U.S.: African American: 47% O-positive, 24% A-positive, and 18% B-positive Latin American: 53% O-positive, 29% A-positive, and 9% B-positive

i believe the answer is a

i believe it is true.