In RNAi, the genes are silenced by the formation of:

The correct answer is Option (1) → ds RNA

Option (1) ds RNA — Correct. In RNAi, a complementary double-stranded RNA (dsRNA) binds to the mRNA of the gene and stops its translation, so the gene is silenced.

Note: A similar question was also asked in CUET (UG) 2023 on 23-06-2023 (Slot 3).

NCERT Extract:
Biotechnological Applications in Agriculture – “… Pest Resistant Plants: Several nematodes parasitise a wide variety of plants and animals including human beings. A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi). RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing).”