How many lac Z genes were present in the cells described in problem 5 that were able to grow on minimal media?

A.	Only 1, the lac Z- allele on the bacterial chromosome.
B.	Only 1, the lac Z+ allele on the bacterial chromosome.
C.	Two, the lac Z- allele on the bacterial chromosome and the lac Z+ allele on the bacterial chromosome.
D.	Two, the lac Z- allele on the bacterial chromosome and the lac Z+ allele on the F' episome.
E.	Only 1, the lac Z+ allele on the F' episome.