According to EPA regulations, which of the following should not be recovered with current EPA-approved recovery devices?

The correct choice indicates that none of the listed substances should be recovered with current EPA-approved recovery devices. This reflects the regulatory guidelines which specify that certain substances are not to be recovered using these devices due to safety and environmental considerations.

Hydrogen, for instance, is a highly flammable gas which presents significant safety risks if not handled properly, making it unsuitable for recovery with standard recovery equipment. Water, while not a refrigerant, can cause operational issues when mixed with refrigerants, as it can lead to corrosion and compromise system integrity. Ammonia is classified as a toxic substance and requires special handling procedures and equipment to recover it safely.

Thus, the correct answer signifies awareness of the nuances in recovery procedures prescribed by the EPA for various substances based on their physical and chemical properties, ensuring safety and compliance with environmental regulations.