Highlight evidence from the text that supports the idea that losing a letter would be dangerous for Washington and the patriots. In the letter he asked for "one of your scrapers as my teeth stand in need of cleaning." That information may not sound like much, but a British intelligence officer would get two valuable bits: the name of a pro-American dentist and, even better, from the return address on the letter, the whereabouts of Washington's headquarters.

—George Washington, Spymaster,
Thomas B. Allen

Which detail provides evidence to support this idea?

The information in the letter does not sound like much.
The return address gives Washington's whereabouts.
Washington's teeth stand in need of cleaning.