Option a, b, c, d * There are three mechanisms of horizontal gene transfer in bacteria:- 1.Transformation 2. Transduction 3. Conjugation (Most common mechanism), It was discovered first by Lederberg and Tatum. * Conjugation plays an impoant role in the transfer of plasmids coding for antibacterial drug resistance and bacteriocin production . * R factor (or the resistance factor) is a plasmid which has two components. o Resistance transfer factor (F) is the plasmid responsible for conjugational transfer(similar to F factor) o Resistance determinant (r): Codes for resistance to one drug. An R factor can have several r determinants.