Which compound is known for extinguishing fires without depleting stratospheric ozone?

Halon-1211 is not the correct choice because it is a compound that contains bromine, which is known to deplete stratospheric ozone. In contrast, the correct answer is ammonium phosphate, which serves as a fire extinguishing agent without contributing to ozone depletion.

Ammonium phosphate works primarily through its ability to cool the fire and chemically inhibit the combustion process, making it effective in suppressing flames. It is commonly used in dry chemical fire extinguishers and for controlling fires involving ordinary combustibles, such as wood and paper. Its effectiveness and environmental safety make it preferable in scenarios where ozone depletion is a concern.

Other options, such as carbon dioxide, while they do not contribute to ozone depletion, are not as universally effective across various types of fires as ammonium phosphate. Aqueous film-forming foam is effective but may not address all fire scenarios and has varied impacts on the environment. Thus, ammonium phosphate stands out as both effective in fire suppression and environmentally responsible.