Which one of the following is not a protein

Answer: Option C

Out of the following given options Ribozyme is not a protein.
Ribozymes are catalytically active RNA molecules or RNA-protein complexes, in which solely the RNA provides catalytic activity. The term ribozyme refers to the enzymatic activity and ribonucleic acid nature at the same time.
Ribozymes are found in the genomes of species from all kingdoms of life.