Which of the following is NOT a type of fuse used on mortar rounds?

The correct choice reflects a misunderstanding in the classification of fuses used with mortar rounds. The PD (Point Detonating) and DLY (Delay) fuses are commonly utilized in artillery and mortar operations. The PD fuse detonates upon impact with the target, while the DLY fuse allows for a delay before detonation, useful for specific tactical scenarios such as airburst or when targeting troops in cover.

The IMP (Impact) fuse also serves a similar role, typically detonating upon contact with the target or at a predetermined distance.

In contrast, the MZB (Multi-zone burst) is not standard terminology associated with mortar fuses. While various fuses can be designed to function in multiple zones (such as air burst or ground burst), "Multi-zone burst" specifically is not a recognized or used type of fuse in the context of mortar rounds. Understanding the various types of fuses and their operational uses is crucial for effective execution in field operations.