Which of the following statements is true about the cycling of oxygen in a pond ecosystem? a. oxygen cannot cycle because it binds irreversibly to other elements. b. cycling of oxygen is independent from cycling of carbon and hydrogen. c. oxygen cycles through the processes of photosynthesis and cellular respiration. d. fish create oxygen through the process of cellular respiration.

The true statement is that Oxygen cycles through the processes of photosynthesis and cellular respiration. During the process of photosynthesis the plants uses carbon dioxide, water and the energy from the sunlight to yield oxygen, simple sugars and energy; while in the process of cellular respiration Oxygen is used together with nutrients such as glucose to yield energy and carbon dioxide.