Author is related to Book in the same way as Choreographer is related to ______.

A word analogy pairs items that share the same relationship as the given pair; the governing relationship here is CREATOR TO PRODUCT — the first term is a professional or creator, and the second term is the defining type of work that creator produces.

Author is related to Book because a book is the defining creative output of an author. Applying the same creator-product relationship, a choreographer is the professional who designs and arranges the sequence of dance movements for a performance, and the work most directly and characteristically produced through choreography is a ballet — a choreographer choreographs a ballet, just as an author authors a book.

Checking the remaining options against the same creator-product test:

• Drama is a broad genre of theatrical writing whose defining creative act belongs to a playwright, not to a choreographer's movement work.

• Masque is a multi-disciplinary courtly entertainment historically credited to its poet or deviser, not to a choreographer as its primary creator.

• Opera is a musical work whose defining creative act belongs to its composer and librettist; choreography is only a supporting element within it, not its defining output.

Only ballet mirrors the author-book creator-product relationship exactly.