This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Microbiology Pa 1 (History, Microscopy, Stains and Structure and Physiology of Bacteria), Subject name: Microbiology
The role of plasmids in conjugation was first described by Lederberg and Tatum (1946) in which bacteria? 
Select and explain. 
A. H. influenza, B. Pseudomonas, C. Escherichia coli, D. M. Tuberculosis
C: Escherichia coli
Answer: C: Escherichia coli 
Explanation: Bacterial conjugation was first described by Lederberg and Tatum (1946) in a strain of E.coli called K12 (carried a conjugative plasmid F) The F factor: The F plasmid, also called F factor, is a transfer factor that contains the genetic information, essential for controlling mating process of the bacteria during conjugation. The F plasmid of Escherichia coli is the prototype for feility plasmids in Gram-negative bacteria. Strains of E. coli with F+ plasmid are called as donors, whereas plasmid are F- behave as recipients.