I don't understand why my answer is wrong. They say that 7 is the maximum # of carriers in the pedigree, but it is possible that both parents in the P generation are carriers. Just because the F1 generation is unaffected doesn't make it impossible for both parents of the P generation to be carriers. The P generation could've been Aa x Aa and their children could've have also been both heterozygous. Isn't my rationale correct?