1: 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

参考答案是e. but，for不能表示目的，所以我选择c.但是我又疑惑，觉得did后面应该加上so.

所以请大家指点。

provide/give clues to sth.

美国传统辞典上for的第一释义就是表目的：Used to indicate the object, aim, or purpose of an action or activity:
为了（用来指一个动作或活动的目的、目标或意图）