Which of the following is a condition that may cause a failure to feed in a shotgun?

A failure to feed in a shotgun often occurs when the action is not cycling properly, which can be attributed to incomplete cycling of the fore-end or slide. This issue can arise from various factors such as inadequate force applied to the action, improper technique, or issues within the shotgun's action components. When the fore-end or slide does not move all the way to the rear or does not return fully forward, it fails to properly chamber a new round, leading to a malfunction.

In contrast, while a dirty weapon can lead to feeding issues over time, it is more directly associated with cycling issues when the gun is clean, making proper cycling the crucial factor in ensuring reliable feeding. Recoil generally affects only the operation of the firearm during shooting rather than the feeding cycle itself, and poor marksmanship does not relate to the mechanics of the shotgun’s operation but rather to the shooter's skill in handling and accurately firing the firearm.