Which boresight is used on the 81mm and 120mm mortar systems?

The M45 boresight is specifically designed for use with both the 81mm and 120mm mortar systems, making it the appropriate choice for this question. Boresighting is an essential process that involves aligning the barrel of the mortar with a designated point or target, ensuring improved accuracy during firing. The M45 boresight is engineered to support the calibration required for these mortar systems, taking into account their specific dimensions and operational characteristics.

In contrast, the other options listed, such as the M44, M46, and M47, are either associated with different types or calibers of mortars or serve other roles within artillery systems, making them unsuitable for the 81mm and 120mm mortar systems. The M45's compatibility with these mortars is crucial for effective operational readiness and accuracy in the field.