Tobacco plants resistant to a nematode have been developed by the introduction of DNA that produced (in host cells) a particular hormone, an antifeedant, a toxic protein, or both sense and anti-sense RNA.

Nematode-specific gene was introduced into tobacco plant via Agrobacterium vector. The introduced DNA produced both sense and antisense RNA which were complimentary to each other and formed dsRNA. This RNA interference caused silencing of nematode-specific mRNA and was lethal for the survival of nematode in tobacco root cells. Thus, the correct answer is option D.