The vector for T-DNA is

- Plant transformation mediated by the soil pathogen, Agrobacterium tumefaciens has become the most used method for plant transformation. - It naturally infects the wound sites in dicots causing the crown gall disease. It is capable to transfer T-DNA of the Tumour inducing (Ti) plasmid into the nucleus of infected cells. - It will then integrate into the host genome and is transcribed, causing the crown gall disease. - Thus, the correct answer is option C.