Which enzyme synthesizes mRNA from a DNA template during transcription?

The enzyme responsible for synthesizing mRNA from a DNA template during transcription is indeed RNA polymerase II. This enzyme specifically catalyzes the transcription of protein-coding genes in eukaryotic cells, where it reads the DNA template and synthesizes a complementary RNA strand.

While "DNA-dependent RNA polymerase" is a term that can refer to the broader class of enzymes capable of synthesizing RNA from a DNA template, this terminology is less commonly employed in the context of eukaryotic transcription, where RNA polymerase II is the specific enzyme that carries out this function in eukaryotic organisms. RNA polymerase I is primarily involved in synthesizing ribosomal RNA (rRNA), and DNA polymerase is responsible for replicating DNA, not synthesizing RNA.

Thus, identifying RNA polymerase II as the enzyme that performs the transcription of mRNA from a DNA template is the most accurate choice in this context.