Respuesta :
D is the sentence where it is used as an interjection. All the other answers use it as a pronoun.
Hope this helps!
D.
A uses boy as a subject, B uses boy as an object, and C uses boy as more of a name. An interjection is an exclamation, like "wow" or "yikes." In sentence D, they are using a somewhat outdated use of boy as an interjection. It usually means surprise or pleasure.