Which of the following is an example of repulsion linkage?
AaBb x AaBb
AaBb x Aabb
AaBb x aabb
AaBb x AAbb
Repulsion linkage, also known as trans linkage, refers to two genes on the same chromosome, but each allele is present on a different homologous chromosome. In the given options, only option C has two alleles on different homologous chromosomes, making it an example of repulsion linkage. In this case, the two genes are A and B, with the alleles A and B present on one chromosome, and a and b present on the other chromosome. This type of linkage can result in the formation of recombinant offspring, which have new combinations of alleles not present in either parent due to crossing over events during meiosis. Options A, B, and D involve genes that are in coupling linkage, as both alleles for each gene are present on the same chromosome.
Option 3 is the correct answer.