In the figure below, the tick marks indicate the positions of restriction sites in two alternative DNA fragments that can be present at a locus in a human chromosome. An RFLP analysis is carried out, using probe DNA that hybridizes with the fragments at the position shown by the rectangle. With respect to this RFLP, how many genotypes are possible? In the depiction of the agarose gel, indicate the genotypes across the top and the phenotype (band position or positions) expected at each genotype.