Final answer:
Phagocytosis is the transport mechanism among the options given that requires energy, in the form of ATP, because it involves moving substances against their concentration gradient.
Step-by-step explanation:
The transport mechanism that requires energy is phagocytosis. Phagocytosis is a process where a cell engulfs large particles or cells, which is an energy-consuming process. This form of cellular eating requires energy, generally in the form of ATP, to move the membrane and cytoplasm around the material to be engulfed.
Active transport mechanisms, like phagocytosis, move substances against their concentration gradient, which is why they require an input of energy. On the other hand, facilitated diffusion, osmosis, diffusion, and movement of ions through ion channels do not require energy as they are forms of passive transport, which uses the concentration gradient to move substances from an area of higher concentration to an area of lower concentration.