Step 1: Understanding Eukaryotic Transcription

In eukaryotic cells, transcription is a complex process involving three distinct types of RNA polymerases, each responsible for synthesizing specific types of RNA molecules.

Step 2: Analyzing RNA Polymerase Functions

The roles of the three RNA polymerases are as follows:

• RNA polymerase I: Transcribes rRNAs (28S, 18S, and 5.8S).
• RNA polymerase II: Transcribes the precursor of mRNA, which is known as heterogeneous nuclear RNA (hnRNA).
• RNA polymerase III: Transcribes tRNA, 5S rRNA, and snRNA (small nuclear RNA).

Step 3: Conclusion

Since the question asks for the enzyme responsible for synthesizing hnRNA, RNA polymerase II is the correct enzyme.