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

Ans E

Only thing I can find wrong with A is are instead of is.