The term ribozyme is applicable to the following molecule in bacteria

The correct answer is Option (2) → 23S rRNA

A ribozyme is an RNA molecule that works as an enzyme. Most enzymes are proteins, but in the ribosome the peptide bond between two amino acids is made by an RNA.

Option (1) mRNA — Incorrect. Messenger RNA carries the genetic code from DNA to the ribosome. It is read as a template; it does not catalyse a reaction.

Option (2) 23S rRNA — Correct. This rRNA of the large subunit of the bacterial ribosome catalyses peptide bond formation during translation, so it is the ribozyme.

Option (3) 5S rRNA — Incorrect. The 5S rRNA is also part of the large subunit in bacteria, but it is a structural RNA; it is not the catalyst.

Option (4) hn RNA — Incorrect. Heterogeneous nuclear RNA is the first transcript in eukaryotes, which is spliced, capped and tailed into mRNA. Bacteria do not make hnRNA.

NCERT Extract:
Translation – “… The cellular factory responsible for synthesising proteins is the ribosome. The ribosome consists of structural RNAs and about 80 different proteins. In its inactive state, it exists as two subunits; a large subunit and a small subunit. When the small subunit encounters an mRNA, the process of translation of the mRNA to protein begins. There are two sites in the large subunit, for subsequent amino acids to bind to and thus, be close enough to each other for the formation of a peptide bond. The ribosome also acts as a catalyst (23S rRNA in bacteria is the enzyme- ribozyme) for the formation of peptide bond.”