Answer: (D) rRNAs
Explanation: In higher eukaryotes, RNA polymerase 1 (also known as Pol I) is the polymerase that only transcribes ribosomal RNA (but not 5S rRNA, which is generated by RNA polymerase III), a form of RNA that accounts for more than half of all RNA synthesised in a cell. Pol I is a 590 kDa enzyme made up of 14 different protein subunits (polypeptides).