Correct Option: B

The T-DNA transfer process of Agrobacterium tumefaciens is activated by the induction of the expression of the Ti plasmid virulence loci by plant signal molecules such as acetosyringone. The overdrive  proteins from acetosyringone-induced Agrobacterium cells interact with T-DNA border and overdrive sequences. The vir gene products act in trans to mobilize the T-DNA element from the bacterial Ti plasmid. The T-DNA is bounded by 25-base pair direct repeat sequences, which are the only sequences on the element essential for transfer. Thus, specific reactions must occur at the border sites to generate a transferable T-DNA copy.