The correct option is A Agrobacterium tumefaciens – Ti Plasmid
Agrobacterium tumefaciens, a pathogen of several dicot plants is able to deliver a piece of DNA known as ‘T-DNA’ to transform normal plant cells into a tumor and direct these tumor cells to produce the chemicals required by the pathogen. This T-DNA is found in the Ti Plasmid of the bacteria. Because it can infect and transmit genetic material successfully into many plant cells, the Ti Plasmid is today used as an effective vector in creating transgenic plants.