The correct option is D 70S
Prokaryotes are unicellular organisms that lack membrane-bound cell organelles. Ribosomes are the organelles made up of proteins and RNA molecules called subunits. These are involved in protein synthesis. The prokaryotic ribosomes are of 70S type, unlike the eukaryotic ribosomes which are of 80S type. The 70S ribosomes are made of 50S and 30S subunits. Thus the correct answer is option D.