Answer:
c. RrMm x RrMm
Explanation:
A dihybrid genotype is the one that is heterozygous for two genes. Hence, a dihybrid cross is a cross between two individuals that are hybrid for alleles of two different loci.
Among the given examples, the cross RrMm x RrMm is a dihybrid cross. Here, both given genotypes are heterozygous or hybrid for two loci (both genotypes have one dominant and one recessive allele for both the genes under study, R and r; M and m).
This cross explains the inheritance of two loci or two genetic traits. Hence, it is an example of dihybrid cross.
