Which of the following characteristics is shared by all cells?

The correct characteristic shared by all cells is the presence of cellular fluid, which refers to the cytoplasm. All cells, whether prokaryotic or eukaryotic, contain cytoplasm, a jelly-like substance that fills the cell and is crucial for various cellular processes. The cytoplasm houses organelles, enzymes, and other molecules necessary for the biochemical reactions that sustain life. This fundamental component facilitates movement within the cell and supports cellular structures, making it essential for all cellular functions.

Other characteristics mentioned in the choices are not universally applicable to all cells. For example, the capacity for photosynthesis is specific to certain organisms, like plants and some bacteria, and does not apply to all cells, especially animal cells. The ability to move independently is typically associated with certain types of cells, such as sperm or some protozoa, and is not a trait found in all cell types. Similarly, respiration mechanisms vary among cells; some may perform aerobic respiration, while others rely on anaerobic processes. Therefore, the presence of cellular fluid is the defining characteristic that unites all cells.