"the rest of harrison's appearance was halloween and hardware." oxymoron, alliteration, allusion, or alliteration and allusion?

Alliteration.

Explanation:

The letter A is used multiple times in the sentence.

what is   the question

  this riddles' answer is library.

  the "leaves" are a reference to the books' pages that the library contains; the branches are a network of libraries that connect multiple libraries' collections, resources, and items in a system of a common database, integrating them; the branches' organization are a useful management tool for coordinating the multiple collections many libraries have.