An E. coli strain is F lac Z met bio. Cells from this strain are mixed with an E. coli strain that is lac Z met bio and carrying an F' episome with the Plac O lac Z DNA sequence on the episome, and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How did these few cells become lac Z met bio?

A.	transformation.
B.	transduction.
C.	sexduction, a special type of conjugation.
D.	conjugation.
E.	transposition.