Sentence Correction

Scientists claim that the discovery of the first authenticated mammal bones in amber
could provide important clues of determining, in addition to how, when mammals
colonized the islands of the West Indies.
A. of determining, in addition to how, when mammals colonized the islands of the
West Indies
B. in the determination of how and when the islands of the West Indies were
colonized by mammals
C. to determine how mammals colonized the islands of the West Indies and when
they did
D. for determining when the islands of the West Indies were colonized by mammals
and how they were
E. for determining how and when mammals colonized the islands of the West Indies

E IMO.
OA plz.

i feel E too...but confused about B