Answer:
The correct answer is option d. "ribosomal RNA".
Step-by-step explanation:
Ribosomal RNA, is the main component of the ribosome and is essential for protein synthesis in all living organisms. Ribosomal RNA has proved to be the most reliable molecule to establish evolutionary relationships among species. The study of the variations in rRNA sequences allowed the establishment of the 3-domain system of classification of all living organisms: Eukaryotes, Bacteria, and Archaea.