You have performed the following mating experiment using Hfr and F- strains of Escherichia coli: Hfr (thr+ leu+ gal+ strs) × F- (thr- leu- gal- strr). Which of the following selective media would you use to score recombinant colonies? A) minimal medium B) minimal medium + streptomycin C) minimal medium + threonine D) minimal medium + streptomycin + threonine