During which cellular process do cells replicate and divide, increasing their numbers?

Cell proliferation refers to the process by which cells undergo replication and division, resulting in an increase in cell numbers. This is a fundamental aspect of growth, development, and tissue repair in multicellular organisms. During cell proliferation, cells go through various phases, including the cell cycle phases of interphase and mitosis, ultimately leading to the formation of two daughter cells from a single parent cell.

In the context of the other options, while cell differentiation involves the process where a less specialized cell becomes a more specialized cell type, it does not necessarily refer to an increase in cell numbers. Similarly, cell metabolism pertains to the chemical reactions that occur within a cell to maintain life, which includes processes like energy production and synthesis of cellular components, but does not imply replication or increase in cell numbers. Cell specialization, on the other hand, refers to the process through which cells develop distinct structures and functions, also without a direct connection to the increase in cell quantities. Therefore, the focus on replication and division in the context of increasing cell numbers distinctly aligns with the concept of cell proliferation.