Introduction:
RNA cleavage is a crucial process in various cellular activities such as gene expression, RNA degradation, and RNA processing. The enzyme responsible for cleaving RNA is called ribonuclease (RNase).

Explanation:
Ribonuclease (RNase):
- Ribonuclease is an enzyme that catalyzes the cleavage of RNA molecules.
- It plays a vital role in various biological processes, including RNA degradation and turnover, RNA processing, and regulation of gene expression.
- There are different types of ribonucleases that have evolved to perform specific functions in different cellular contexts.

DNase:
- DNase is an enzyme that cleaves DNA molecules, not RNA.
- It is responsible for degrading DNA and plays a role in DNA repair, chromatin remodeling, and other DNA-related processes.

Ligase:
- Ligase is an enzyme that catalyzes the joining of two molecules by forming a covalent bond between them.
- It is involved in DNA repair, DNA replication, and other processes that require the joining of DNA or RNA fragments.

Protease:
- Protease is an enzyme that cleaves peptide bonds in proteins, not RNA.
- It is responsible for protein degradation, protein processing, and regulation of protein function.

Conclusion:
The enzyme that cleaves RNA is ribonuclease (RNase). It is specifically designed to recognize and cleave RNA molecules, playing essential roles in RNA degradation, processing, and gene expression regulation. DNase cleaves DNA, ligase joins molecules, and protease cleaves peptide bonds in proteins.