Read the following statements regarding cloning vectors. (A) Agrobacterium tumefaciens delivers a piece of DNA known as T-DNA to transform normal plant cells into a tumor. (B) Agrobacterium tumefaciens is a pathogen of several monocot plants. (C) Retroviruses in animals have the ability to transform normal cells into cancerous cells. (D) For gene transfer in plants, the Ti plasmid is modified into a disarmed cloning

Step-by-step solution

Statements (A), (C), and (D) are correct. Statement (B) is incorrect because Agrobacterium tumefaciens is a pathogen of several dicot plants, not monocots. It delivers T-DNA to transform normal dicot cells into tumors and directs them to produce chemicals required by the pathogen. Retroviruses similarly transform normal animal cells into cancerous cells. Both the Ti plasmid and retroviruses are disarmed to be used as non-pathogenic cloning vectors for delivering genes of interest into plant and animal cells respect