Correct Answer - a
Agrabacterium tumefaciens (updated scientific name: Rhizobium radiobacter) is the causal agent of crown gall desease ( the formation of tumour ) in over 140 species of dicot. It is a rod-shaped, Gram negative soil bacterium (Smith, et. Al, 1907). Symptoms are caused by the insertion of a small segment of DNA, known as T-DNA (transfer DNA) into the plant cell, which is incomporated at a semi-random location into the plant geneme.
