Final answer:
In phagocytosis, the signal that attaches to apoptotic bodies is called a cell-surface receptor.
Step-by-step explanation:
In phagocytosis, the signal that serves as a signal attached to apoptotic bodies for other cells to eat the apoptotic bodies is called a cell-surface receptor. Cell-surface receptors are proteins on the surface of cells that can receive signals from the environment and transmit them into the cell. In this case, the cell-surface receptor recognizes the apoptotic bodies and triggers the process of phagocytosis, where the cells engulf and digest the apoptotic bodies.