The correct option is D There are composed of ribonucleic acid and proteins
Ribosomes are non-membranous organelles that are found in both eukaryotic and prokaryotic cells. They comprise of an RNA component as well as a protein component.
"These are found only in eukaryotic cells " is incorrect, since they are found in both prokaryotic as well as eukaryotic cells.
"These are self-splicing introns of some RNAs. " is incorrect, since self-splicing introns are ribozymes.
"The prokaryotic ribosomes are 80 S, where 'S' stands for sedimentation coefficient." is incorrect, since prokaryotic ribosomes are 70S, where S stands for Svedberg unit.