Silencing of specific mRNA is possible via RNAi because of -

The correct option is Complementary dsRNA.

Step-by-Step Explanation:

1. Understanding RNA Interference (RNAi): RNAi is a biological process in eukaryotic cells where RNA molecules inhibit gene expression or translation. This mechanism is primarily used by cells to defend against viral infections and control the activity of transposons (jumping genes), as well as to regulate cellular gene expression.

2. Mechanism of Silencing: The RNAi process is initiated by the introduction of double-stranded RNA (dsRNA) into the cell. This dsRNA is complementary to the specific target mRNA transcript that needs to be silenced.

3. Role of Dicer: An enzyme named Dicer cleaves the long dsRNA into short double-stranded fragments called small interfering RNAs (siRNAs), which are typically 21 to 23 nucleotides long.

4. RISC Activation and Silencing: These siRNA fragments are then loaded into a multi-protein complex known as the RNA-induced silencing complex (RISC). The RISC unwinds the dsRNA, discarding one strand (the passenger strand) and keeping the other (the guide strand). The guide strand, which is complementary to the target mRNA, guides RISC to bind specifically to that mRNA. Once bound, the catalytic component of RISC (often an Argonaut protein) cleaves the target mRNA, preventing it from being translated into a protein.

5. Conclusion: Therefore, silencing of specific mRNA is made possible via RNAi because of the initiation by complementary dsRNA.