Which type of RNA is primarily associated with eukaryotic RNA polymerase II?

The type of RNA that is primarily associated with eukaryotic RNA polymerase II is messenger RNA (mRNA). RNA polymerase II is responsible for transcribing protein-coding genes, which is the process by which the genetic information in DNA is used to synthesize mRNA. This mRNA then serves as a template for protein synthesis during translation.

The role of RNA polymerase II in synthesizing mRNA is crucial because it not only creates the single-stranded RNA copy of the gene but also undergoes several processing steps, such as capping, polyadenylation, and splicing, to produce mature mRNA that can be translated into proteins. Thus, the connection of mRNA with RNA polymerase II highlights its fundamental role in gene expression and protein synthesis in eukaryotic cells.