Select the correct statement about the RNAi method.

Options

A. RNAi strategy was taken up to prevent the infestation of nematodes in the roots maize plants.
B. This method involves the use of a complementary dsRNA molecule that binds to ans prevents translation of the mRNA
C. Only RNA genomes of viruses can be used as a source for the complementary RNA
D. Mobile genetic elelments called transposons can replicate only through a DNA intermediate

Answer

To solve the question regarding the correct statement about the RNA interference (RNAi) method, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding RNAi**:
- RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. It is a crucial mechanism for regulating gene expression and defending against viral infections in eukaryotic cells.

2. **Analyzing Option 1**:
- The first statement claims that "RNAi strategy was taken up to prevent the infestation of nematodes in the roots of maize plant."
- This statement is **incorrect** because RNAi is primarily used in the context of certain plants like tobacco to combat nematode infestations, not specifically maize.

3. **Analyzing Option 2**:
- The second statement says, "This method involves the use of complementary dsRNA that binds to and prevents the translation of mRNA."
- This statement is **correct**. RNAi utilizes double-stranded RNA (dsRNA) that is complementary to the target mRNA, leading to the degradation of the mRNA and preventing its translation.

4. **Analyzing Option 3**:
- The third statement states, "Only RNA genomes of viruses can be used as a source of the complementary RNA."
- This statement is **incorrect** because RNAi can utilize various sources of RNA, not just viral RNA genomes. It can also involve transposable elements and other RNA sources.

5. **Analyzing Option 4**:
- The fourth statement claims, "Mobile genetic elements called transposons can replicate only through a DNA intermediate."
- This statement is **incorrect**. Transposons can replicate through both DNA and RNA intermediates, depending on the type of transposon.

### Conclusion:
- The only correct statement about the RNAi method is **Option 2**: "This method involves the use of complementary dsRNA that binds to and prevents the translation of mRNA."