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 ffice:smarttags" />New World tropical birds that includes more than 230 species and that are represented in virtually every kind of habitat.fficeffice" />

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

答案给的是B，我选的C。我觉得定语从句修饰的是birds而不是a group。

请大家指点一下，多谢了！

Please help! Thanks very much!