Using the rii mutant bacteriophage and e. coli strains b and k, seymour benzer studied gene structure by both recombination and complementation. wild-type phages form plaques on strains b or k; rii forms plaques on b only. in one set of experiments, benzer infected e. coli strain b simultaneously with two different rii mutants. progeny phages were collected and used to infect strain k, and, occasionally, plaques formed. in a second set of experiments, benzer infected strain k simultaneously with high amounts of two different rii mutant phages. occasionally, plaques were observed from this infection. which set of experiments shows recombination, and which demonstrates complementation? explain the difference.