Which cellular structure is responsible for the synthesis of ribosomal RNA?

The nucleus is the correct choice for the structure responsible for the synthesis of ribosomal RNA (rRNA). Within the nucleus, there is a specialized region known as the nucleolus, where rRNA is transcribed from DNA. This rRNA then combines with proteins to form the subunits of ribosomes, which are essential for protein synthesis in the cell.

The nucleus serves as the control center for cellular activity and houses the cell's genetic material, making it the primary location for transcription processes, including rRNA synthesis. Once rRNA is produced, it is transported out of the nucleus to the cytoplasm, where it plays a crucial role in the formation of ribosomes.

Understanding the function of the nucleus in the synthesis of rRNA highlights its critical role in gene expression and cellular function, differentiating it from other cellular structures like the ribosome, which primarily functions in protein synthesis, and the mitochondria and Golgi apparatus, which have distinct roles in energy production and protein processing, respectively.