What devices keep the spray mixture in the tank from escaping back through the hose into a water source?

The correct choice is related to devices designed to prevent the backflow of a liquid into a water source, particularly in the context of spray mixture tanks used in pest control. Antisiphoning devices serve this purpose by ensuring that the liquid does not flow backward through the hose and contaminate drinking water sources or other water systems.

Antisiphoning is specifically concerned with preventing siphoning, which could occur if a drop in pressure allows the liquid in the tank to be drawn back into the water supply. These mechanisms work by effectively creating a barrier that stops the reverse flow of the spray mixture.

Other options, while relevant to backflow prevention and commonly used in plumbing and pest control settings, do not specifically align with the definition of antisiphoning. Backflow preventers and check valves primarily focus on preventing backflow in a general sense, but antisiphoning directly addresses the concern of siphon action that could lead to contamination, making it the most appropriate term for this context.