Answer:
F. The giant water reed which Egyptians used to manufacture writing material
Explanation:
An appositive phrase is a noun or a noun phrase that renames, identifies or gives further information of another noun placed right beside it. In the sentence, although the phrase "The giant water reed which Egyptians used to manufacture writing material" is long, it functions as an appositive phrase because it gives further information of the noun "papyrus", plus, the phrase is right beside "papyrus".
