Among the RNA polymerases, the RNA polymerase-II transcribes:

Options

A. r-RNA
B. t-RNA
C. Small nuclear RNAs
D. Heterogenous nuclear RNA

Answer

**Step-by-Step Solution:**

1. **Identify the Types of RNA Polymerases:**
- There are three main types of RNA polymerases in eukaryotic cells: RNA polymerase I, RNA polymerase II, and RNA polymerase III.

2. **Understand the Function of Each RNA Polymerase:**
- **RNA Polymerase I**: This enzyme is responsible for transcribing ribosomal RNA (rRNA), specifically the 28S, 18S, and 5.8S rRNA.
- **RNA Polymerase II**: This polymerase transcribes messenger RNA (mRNA) and its precursor, known as heterogeneous nuclear RNA (hnRNA).
- **RNA Polymerase III**: This enzyme transcribes transfer RNA (tRNA) and 5S ribosomal RNA.

3. **Focus on RNA Polymerase II:**
- The question specifically asks about RNA polymerase II. We need to determine what it transcribes.

4. **Identify the Product of RNA Polymerase II:**
- RNA polymerase II transcribes hnRNA, which is the precursor to mRNA. After processing, hnRNA is converted into mature mRNA.

5. **Conclusion:**
- Among the RNA polymerases, RNA polymerase II transcribes heterogeneous nuclear RNA (hnRNA), which is the precursor to mRNA.

**Final Answer:**
RNA polymerase II transcribes heterogeneous nuclear RNA (hnRNA).

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