In what manner is the sheaf adjusted for mortars during a registration?

The correct answer focuses on the method used to adjust the sheaf pattern for mortars during registration. When registering mortars, the sheaf is aligned with a specific spread pattern to ensure effective coverage of the target area and to account for the inherent dispersion of mortar rounds.

In this case, aligning the sheaf with a 40 meter lateral spread, perpendicular to the gun-target line is critical. This method helps to concentrate the fire in a manner that maximizes the probability of affecting the target area while considering the mortar's capabilities and the operational requirements.

The perpendicular alignment to the gun-target line is particularly important in this context because it ensures that the adjustments being made account for the direct line of sight and the trajectory of the mortar rounds, allowing for precise targeting and reducing the likelihood of missing the intended zone.

Other options propose different lateral spreads or alignments that do not conform to standard practices for mortars during a registration process, such as using incorrect distances or aligning with the observer-target line instead of the gun-target line, which would not be suitable for ensuring accuracy and effectiveness in targeting.