Agnes Has Been Using XQuery to Design Queries Using Path

Multiple Choice

Agnes has been using XQuery to design queries using path expressions. Her next project will involve multiple source documents and require more complicated criteria. She has heard that a FLWOR structure could be effective for such cases, and comes to you for assistance in developing a FLWOR structure query.
-Agnes is confused by the rules about how many of each type of clause are required in a FLWOR structure. You tell her that in a FLWOR structure, the _____ clause is optional.

A) where
B) for
C) let
D) return