What are the three principal parts of a cell?

The three principal parts of a cell are the plasma membrane, nucleus, and cytoplasm. The plasma membrane is a vital structure that regulates what enters and exits the cell, thus maintaining the internal environment. The nucleus acts as the control center, housing the cell's genetic material and coordinating activities such as growth, metabolism, and reproduction. Lastly, the cytoplasm is the jelly-like substance that fills the cell and contains various organelles, facilitating the processes necessary for cell survival and function.

While options that mention "cell membrane" or "cell wall" refer to structures associated with cells, the term "plasma membrane" is more precise in the context of eukaryotic cells. The other options either introduce components that are not fundamental parts of a typical cell or include the cell wall, which is present primarily in plant cells and some prokaryotes but is not a universal component of all cells. Additionally, options including mitochondria emphasize an organelle instead of focusing on the three basic structural components of a cell.