Bt toxin produced by Bacillus thuringiensis is resistant to:

The correct answer is Option (2) → Insects

Option (1) Drought — Incorrect. Bt toxin has nothing to do with water stress.

Option (2) Insects — Correct. Bt toxin kills the insects that eat the plant, so crops carrying the Bt gene are resistant to insect pests. The toxin does not act against drought, nematodes or viruses.

Option (3) Nematodes — Incorrect. NCERT protects plants against the nematode Meloidogyne incognitia by RNA interference, not by Bt toxin.

Option (4) Viruses — Incorrect. Bt toxin acts in the insect gut; it does not act on viruses.

Note: Bt toxin kills the insects that eat it; it is the Bt crops carrying the toxin gene that are resistant to insects.

NCERT Extract:
Biotechnological Applications in Agriculture – “… Bt Cotton: Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.”