The Plant Disease Called Crown Gall Is Caused by the

The plant disease called crown gall is caused by the

A) insertion into plant cells of a T DNA element carried on the Ti plasmid.
B) transcription of the Ti plasmid in the plant cells.
C) translation of the Ti plasmid in the plant cells.
D) rampant multiplication of Agrobacterium tumefaciens bacteria within the plant.
E) transfer of bacterial genomes into the plant cell genome.