Answer:
"F" on account of E.coli show the fertility factor. Cells possessing this factor (called donors) hold the ability to move the hereditary material over the strains by a procedure called conjugation. F-factor exists as a free element (cell is called episome) or integrated into bacterial chromosome (cell is called Hfr-High frequency recombinant). Cells with no F factor are recipients.
In a Conjugation between a F+ and F-cell just F factor from F+ cell gets moved o produce two F+ cells. But during a Hfr and F-conjugation as the F factor is incorporated into the chromosome and by the intrinsic idea of F factor to get moved the Hfr cells attempt to move their whole genetic material across and there are two outcomes wherein one case there is a fragmented exchange of hereditary material and the recipient cell remain F-and when there is a finished exchange of hereditary material the cell becomes Hfr yet this is uncommon as the time taken for the total exchange of hereditary material is excessively long for the cells to remain contact.