What are the blood types possible in offspring if both parents have 0 positive group?

The possible blood types in offspring if both parents have O positive group are:

1. O positive (OO)

2. O negative (OO)

Since both parents have O positive blood type, they each have two O alleles. When they produce gametes, each gamete will carry one O allele. Therefore, all possible offspring will have the OO genotype and either O positive or O negative blood type.