Biology - Allele effect

Could anyone please help me determine the possible answer to this question? Unfortunately, the answer key hasn’t been provided.


i feel like the answer should be A)
take the co-dominant gene for blood types A and B
(in this scenario we can only be AA BB or AB)

in heterozygous individuals AB have both A and B antigens thus both have some effect on the phenotype of the cell

in homozygous individuals AA, the A phenotype is proportionally more expressed on the cell surface, thus it has a greater effect on phenotype