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You perform interrupted-mating experiments on three Hfr strains (A, B, and C). Genes are transferred (from last to first) in the following order from each strain: strain A, thi-his-gal-lac-pro; strain B, azi-leu-thr-thi-his; strain C, lac-gal-his-thi-thr. How are the F factors in these strains oriented?