The blood serum from one individual (let's call this person individual 1) is known to agglutinate the

Question:

The blood serum from one individual (let's call this person individual 1) is known to agglutinate the red blood cells from a second individual (individual 2). List the pairwise combinations of possible genotypes that individuals 1 and 2 could be. If individual 1 is the parent of individual 2, what are his or her possible genotypes?