Transgenic plants are produced by using Ti plasmid from the

The correct option is A Agrobacterium tumefaciens
A Ti or tumour inducing plasmid is a circular plasmid that is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium rhizogenes use to transduce its genetic material to plants. The Ti plasmid is lost when Agrobacterium is grown above 28${}^o$C. Such, cured bacteria do not induce crown galls, i.e., they become avirulent.