Which of the following is a function of cells?

• A. Photosynthesis
• B. Digestion
• C. Respiration
• D. Covering, lining, storage, movement, connection, defence, communication, reproduction

Answer: (D)

Cells have many roles that keep organisms functioning, not just a single task. They form tissues and perform diverse activities such as covering and lining surfaces (epithelial cells), storing substances (like fat or glycogen in specialized cells), enabling movement (muscle cells), forming connections and networks (neural and other cell junctions), defending the body (immune cells), communicating signals (cell receptors and signaling), and enabling reproduction (gametes). This broad set of functions across different cell types illustrates why the broad list of roles is the best answer. By contrast, photosynthesis is restricted to cells with chloroplasts in plants and some microorganisms, digestion involves specific cells in the digestive system, and respiration is a common cellular process but is just one aspect of cell function rather than the wide range described.