During preflight, what should you check for with the Sniffle Valves?

The correct answer emphasizes that during preflight inspections, it is crucial to ensure that a single drop of fuel is not actively dripping from the Sniffle Valves. These valves play an important role in regulating fuel pressure and preventing the spillage of fuel. The presence of any active dripping can indicate a malfunction or improper sealing, which poses significant safety risks such as potential fire hazards or fuel system inefficiencies.

It's important to note that the other factors regarding fluid leaks, air flow, and unobstructed entrances are also relevant in the overall context of aircraft maintenance and safety checks, but the specific focus on ensuring that there is no active dripping directly addresses the operational integrity of the fuel system. A single drop of fuel indicates that there may be an issue that needs to be rectified before the aircraft can be deemed safe for operation.