What structure inside the nucleus is responsible for producing ribosomes?

The structure responsible for producing ribosomes within the nucleus is the nucleolus. The nucleolus is a dense region found inside the nucleus where ribosomal RNA (rRNA) is synthesized and combined with proteins to form the subunits of ribosomes. Once the ribosomal subunits are assembled in the nucleolus, they are then transported out of the nucleus into the cytoplasm, where they combine to become functional ribosomes, essential for protein synthesis.

In contrast, the nucleus serves as the control center of the cell and houses genetic material but does not directly produce ribosomes. The rough endoplasmic reticulum is involved in the synthesis and processing of proteins that will be secreted or membrane-bound, but it does not synthesize ribosomes itself. Chromatin, which is composed of DNA and proteins, plays a role in packaging the genetic material inside the nucleus but is also not involved in ribosome production. Therefore, the nucleolus is specifically designated for the assembly of ribosomal components, making it the correct answer.