The globin gene family in mammals, birds, and reptiles is organized into ?- and ?-globin gene clusters that are located on two different chromosomes. In most fish and amphibians, however, the globin genes are close to each other on one chromosome. At which point (A to E) in the following simplified phylogenetic tree is a chromosomal translocation likely to have happened that placed the ?- and ?-globin genes on two separate chromosomes?