When casing letter mail, how much should a letter carrier pick up?

When casing letter mail, the appropriate amount of mail a letter carrier should pick up is governed by ergonomic guidelines to ensure safety and efficiency while carrying. Picking up no more than 2 inches in the left hand is designed to help balance the load and prevent potential strain or injury while allowing for the best possible grip and control of the mail. This approach promotes a safer working environment and enhances the carrier's ability to navigate their route effectively.

The other options suggest either an unmanageable amount of mail or a measurement that doesn't align with established guidelines, which could lead to risks associated with overloading or improper handling of the mail. Hence, selecting the right quantity for safe handling practices is crucial in the daily operations of a letter carrier.