What are the maximum dimensions for a standard letter?

The maximum dimensions for a standard letter as defined by postal regulations must fit within specific limits to qualify for standard letter pricing and handling. The correct answer accurately reflects these regulations, which specify that a letter must not exceed 11.5 inches in length, 6.125 inches in height, and 0.25 inches in thickness.

This choice meets the necessary criteria for thickness, ensuring that it isn't too bulky for standard letter classification. Choosing this option demonstrates an understanding of the Postal Service's guidelines for acceptable letter dimensions, which is important for proper mailing practices. By adhering to these specifications, senders can ensure that their mail is processed efficiently and at the correct rate.

The other options, while they may appear reasonable at first glance, either exceed the maximum allowable length or height, which would categorize them differently in postal processing, potentially leading to higher postage costs or different handling procedures.