What is a major function of the nucleolus?

The nucleolus is primarily responsible for the production of ribosomal RNA (rRNA), which is an essential component of ribosomes. Ribosomes are the cellular structures where protein synthesis occurs, and they consist of both rRNA and proteins. The nucleolus assembles rRNA and combines it with ribosomal proteins to form the subunits of ribosomes. These subunits are then transported out of the nucleolus and into the cytoplasm, where they play a crucial role in translating messenger RNA (mRNA) into proteins, which are vital for many cellular functions.

The other options relate to different cell functions. For instance, storing DNA is a role of the nucleus, while digesting waste materials pertains to lysosomes. Transporting proteins is mainly handled by the endoplasmic reticulum and Golgi apparatus, which are involved in the modification and transport of proteins within the cell. Understanding the specific functions of cellular organelles helps clarify how cellular processes are interconnected.