Final answer:
The proper action is to inflate the underinflated tire to the recommended pressure level.
Step-by-step explanation:
When performing a Before Operations Preventive Maintenance Checks and Services (PMCS), if you notice that the front right tire appears slightly underinflated, the proper action would be to inflate the tire to the recommended pressure level. It is important to ensure that all tires are properly inflated for safe operation of the vehicle. Underinflated tires can lead to reduced fuel efficiency, tire wear, and poor handling.