A 7/16 bolt generally takes a:
5/8 wrench, 7/16 wrench, 11/16 wrench or 3/4 wrench?

Bolt Markings (http://www.unified-eng.com/scitech/bolt/headsize.html)

I'm wondering if this isn't a trick question.

From an engineering standpoint you'd use things like e.g. 1/4-20 bolt. From a mechanics standpoint you might refer to the head size.