What is the primary function of the nucleus in eukaryotic cells?

The primary function of the nucleus in eukaryotic cells is to store and manage genetic material. The nucleus serves as the control center of the cell, containing the cell's DNA, which is organized into chromosomes. This DNA holds the instructions necessary for the development, functioning, growth, and reproduction of the cell.

Inside the nucleus, the genetic material is not only stored but also regulated. The processes of transcription and replication involve copying information from DNA to RNA, which can then be used to synthesize proteins. This makes the nucleus essential for controlling gene expression and ensuring that the correct proteins are produced at the right times and in appropriate amounts.

By regulating who has access to the genetic information and managing the various steps involved in gene expression, the nucleus plays a critical role in maintaining the overall function and identity of the cell. The other choices pertain to distinct cellular processes or functions that occur in different parts of the cell, such as energy production in mitochondria, protein synthesis in ribosomes, and cellular signaling through various pathways involving receptors and signaling molecules.