Select the most appropriate meaning of the given idiom.

A dry run

a rehearsal

The most appropriate meaning of the idiom "a dry run" is a rehearsal. It is an informal expression that means to practice something beforehand, without actually doing it for real. The idiom is thought to have originated in the early 20th century, and it is believed to be a reference to the fact that a dry run is like a rehearsal, in that it does not involve any real consequences.

The other options for the meaning of the idiom are incorrect. A poor harvest is not a rehearsal. A slow run is not a rehearsal. A run on dry ground is not a rehearsal.