What part of the cell is primarily responsible for cellular control?

The nucleus is the part of the cell that is primarily responsible for cellular control. It houses the cell's genetic material (DNA), which contains the instructions for the development, functioning, and reproduction of the cell. The nucleus regulates gene expression and controls the synthesis of proteins that are essential for various cellular processes. By managing the information encoded in DNA, the nucleus plays a critical role in determining how the cell responds to internal and external signals, making it the control center of the cell.

In contrast, the cytoplasm is the gel-like substance where most cellular processes occur, but it does not contain the genetic material. The cell membrane, while important for protecting the cell and regulating what enters and exits, does not control cellular functions or processes. The Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles, but it does not regulate cell activity at the genetic or command level. Therefore, the nucleus stands out as the central hub for cellular control, making it the correct answer.