Which annunciator indicates that the pressure differential in the fuel filter is too high?

The annunciator that indicates the pressure differential in the fuel filter is too high is the L/R FUEL FILTER BYPASS. This warning system is designed to alert the pilot that the fuel filter has reached a point of blockage or contamination, causing an increase in pressure differential.

When the differential pressure exceeds a specific threshold, it may indicate that the fuel filter is not functioning optimally, which can result in reduced fuel flow to the engines. The bypass system allows for fuel to continue flowing even when the filter is compromised, but it also serves as an important indicator for the pilot to evaluate the condition of the fuel system and potentially take corrective action.

Other options, such as the fuel feed and wing tank overpressure indications, pertain to different issues within the fuel system and do not directly relate to the filtration process or its efficiency. The focus on the bypass specifically points to the condition of the fuel filter, making it the correct choice in this context.