When Swamp Sparrows Are Raised in Isolation and Exposed Only

When swamp sparrows are raised in isolation and exposed only to recordings of patterns of mixed songs from song sparrows and swamp sparrows, they

A) never produce a song.
B) still produce syllables typical of their own species.
C) still produce their species' birdsong.
D) produce a song that is a mixture of song sparrow and swamp sparrow syllables.