GMAT考试SC语法题The Glass House Mountains求解答

GMAT考试SC语法题The Glass House Mountains求解答
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