求助！ 对OG12-001 官方解释的疑惑

小厨子

OG12-1
?? The Glass House Mountains in Queensland, Australia,
were sighted in 1770 by the English navigator Captain
James Cook, by whom they were named supposedly
because its sheer wet rocks glistened like glass.
?? (A) by whom they were named supposedly because its
?? (B) by whom they were named supposedly and their
?? (C) naming them supposedly since their
?? (D) who so named them supposedly because their
?? (E) who so named it since supposedly their

C As the object of a preposition and not the subject of the
clause, James Cook does not work as the noun that the
verbal phrase beginning with naming can describe
; the preposition
since loses the important causal logic of the sentence

虽然C选项能靠前面排除，
但是，不能明白OG为什么把since看成prep，此处把glinsten看成verb的话，since可以做conj表因果的啊
求N人指教，不胜感激！

lonelyorchid

OG所说的介词是by the English navigator Captain James Cook中的by好吧...

ccmoom

ls的。og所说的介词就是since 呀。
 ……  书上是斜体。
楼主，你可以查一查since 、because、 for的差别，以前的讨论帖都有的。
 简单来说。because有很强的因果联系。since和for倾向于大家都知道的事实的那种“因果”联系。
这道题上不属于后面那种，应该用because。  
 我是菜鸟，错了勿怪。