Under what circumstance can you remove the supplementary charge?

The correct choice highlights a specific condition where the supplementary charge can be safely removed. When using a long intrusion VT fuze, the supplementary charge may be removed because this type of fuze is designed to operate effectively without the additional charge. The long intrusion VT fuze is calibrated to detonate based on proximity or time, thus not requiring the supplementary charge to achieve the desired effect.

In contrast, during a misfire or a malfunction, the priority would be to ensure safety and address the situation without removing any elements that could lead to unintended detonation or further complications. Similarly, while the howitzer is in storage, all components, including the supplementary charge, should remain intact to maintain the integrity of the system and ensure readiness for operation when needed. Thus, the unique operational context of the long intrusion VT fuze makes it the appropriate scenario for the removal of the supplementary charge.