Final answer:
Jesse should use kilograms to measure the weight of a package containing books and documents for postage. This unit is most appropriate due to the likely substantial combined weight of these items.
Step-by-step explanation:
The student's question revolves around determining the appropriate metric unit for measuring the weight of a package that contains books and documents. In situations like these, it is important for individuals such as Jesse, who works in a mailroom, to select a unit of measurement that is convenient and commonly used for postal services. The choice between milligrams, grams, and kilograms depends on the total weight of the items being sent.
Since books and documents can collectively have a substantial weight, the most suitable metric unit for Jesse to use would be kilograms. Milligrams are too small for such a package, as a book could weigh millions of milligrams. Grams could also be considered impractical for this purpose because the total weight can easily reach thousands of grams. Kilograms, being a larger unit, are better suited when dealing with the weight of several books and documents, streamlining the process of calculating the correct postage.