Correct Option: A

E. coli is the bacteria which are known to be naturally competent for transformation of DNA. It offers many advantageous such as : ​​
Genetic simplicity : E. coli cells only have about 4,400 genes whereas the human genome project has determined that humans contain approximately 30,000 genes. E. coli, live their entire lifetime in a haploid state. ​​
Growth rate : E. coli grows rapidly at a rate of one generation per twenty minutes under typical growth conditions. ​​
Safety : E. coli is naturally found in the intestinal tracts of humans and animals where it helps provide nutrients (vitamins K and B12) to its host. ​​
Conjugation and the genome sequence : The E. coli genome was the first to be completely sequenced. Genetic mapping in E. coli was made possible by the discovery of conjugation.
Ability to host foreign DNA : E. coli is readily transformed with plasmids and other vectors, easily undergoes transduction, and preparation of competent cells (cells that will take up foreign DNA) is not complicated.