What is indicated by the inner probe of the wing fuel?

The inner probe of the wing fuel tank in the T-6A primarily indicates the remaining fuel quantity as the fuel level depletes. This probe provides an approximate reading and is most useful when fuel levels are low. When the reading dips to about 20 pounds, it signals that the fuel is critically low, allowing pilots to make informed decisions about fuel management before the tank runs dry.

This option reflects the function of the inner probe accurately as it is designed to warn pilots of low fuel levels rather than provide precise measurements. The other choices imply more exact or different quantities that do not correspond to the actual performance or purpose of the inner probe in the fuel management system of the T-6A.