What are three maximum punishments that a commanding officer holding the rank of major or above can impose in NJP?

The correct choice outlines the appropriate maximum punishments that a commanding officer of the rank of major or higher can impose under Non-Judicial Punishment (NJP) according to the Uniform Code of Military Justice (UCMJ) and established Marine Corps regulations.

In this context, correctional custody for 30 days serves as a significant punitive measure that can detain a service member for a period where structured, supervised confinement occurs but does not involve full imprisonment. The option to reduce to the lowest or any intermediate grade recognizes the flexibility a commanding officer has in terms of consequences for underperformance or misconduct. Additionally, imposing restriction for 45 days provides a substantial consequence, as it limits the service member's ability to move freely and partake in activities outside of duty, affecting both personal freedom and morale.

By addressing these three forms of punishment, this option reflects the balance between corrective discipline and the authority granted to higher-ranking officers. Such measures aim to maintain order and discipline while allowing offenders the opportunity to improve through structured rehabilitation. The combination of these punishments aligns well with the overarching goals of maintaining military readiness and discipline.