Unlike most warbler species, the male and female blue-winged warbler are very difficult to tell apart.
(A) Unlike most warbler species, the male and female blue-winged warbler are very difficult to tell apart.
(B) Unlike most warbler species, the gender of the blue-winged warbler is very difficult to distinguish.
(C) Unlike those in most warbler species, the male and female blue-winged warblers are very difficult to distinguish.
(D) It is very difficult, unlike in most warbler species, to tell the male and female blue-winged warbler apart.
(E) Blue-winged warblers are unlike most species of warbler in that it is very difficult to tell the male and female apart.

Please explain..