In generalized transduction, a phage introduces a segment of donor DNA into the recipient cell. This is followed by recombination of the donor fragment with the recipient chromosome. Which of the following must occur?
◦ circularization of the donor fragment before recombination
◦ a pair (or even number) of crossovers between the donor segment and the recipient
◦ degradation of one of the two strands of phage genome
◦ replication of the donor segment before recombination
◦ a single crossover between the donor segment and the recipient chromosome