A South American bird that forages for winged termites and other small insects while swinging upside down form the foliage of tall trees, the graveteiro belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and that are represented in virtually every kind of habitat.

(a)graveteiro belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and that are
(b)graveteiro belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and is
(c)graveteiro belongs to the ovenbird family, a group of New World tropical birds that include more than 230 species and is
(d)graveteiro, which belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and that are
(e)graveteiro, which belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and is

答案是B。我想问为什么不选C，that 修饰birds 所以后面动词用复数include, and 之后的动词因为修饰a group of......所以是用单数is。