Practice question

Question

Q138 While designing an experiment for Agrobacterium mediated plant transformation, a student noted down the following points: A. Ti and Ri plasmids induce crown gall and hairy root disease, respectively B. Enzymes octopine synthase and nopaline synthase involved in the synthesis of octopine and nopaline, respectively are encoded by T-DNA. C. All the six vir genes, vir A, vir B, vir C, vir D, vir E and vir G are absolutely required for virulence. D. Almost perfect 25 bp direct repeat sequences flanking all Ti and Ri plasmids in the T-DNA region is essential for T-DNA transfer. Which one of the following combinations of the above statement is correct?