How is the sheaf adjusted when using mortars during registration?

The correct choice highlights the proper adjustment of the mortar sheaf during the registration process, which is crucial for achieving accurate fire. By adjusting the sheaf on line with a 40 meter lateral spread and ensuring it is perpendicular to the gun-target line, the mortars can effectively account for factors such as dispersion and wind, enhancing the precision of the rounds fired.

This method allows for a more controlled spread of munitions around the target area, which is essential for effective targeting and minimizing collateral damage. Mortar adjustments during registration focus on establishing a baseline relationship between the firing point and the target to achieve the desired impact of rounds in a specific area. Having the spread aligned with the gun-target line rather than the observer-target line directly ties the adjustment to the actual point of fire, ensuring that the rounds are deployed accurately towards the intended target location.

Utilizing a 40 meter spread is a standard practice that balances effectiveness with control over the delivered munitions, which is critical in close support operations. Other spreads mentioned, as well as aligning to the observer-target line, do not follow the established procedures that ensure optimal accuracy in mortar operations.