另一道哦～ 来自XDF蓝皮语法

sassyangel913

P94.11.
Affording strategic proximity to the Strait of Gibraltar, Morocco was also of interest to the French throughout the first half of the twentieth century because they assumed that if they did not hold it, their grip on Algeria was always insecure.  （B）
(A) if they did not hold it, their grip on Algeria was always insecure
(B) without it their grip on Algeria would never be secure
(C) their grip on Algeria was not ever secure if they did not hold it
(D) without that, they could never be secure about their grip on Algeria
(E) never would their grip on Algeria be secure if they did not hold it

这个题我纠结于B和E， A和C中的状语从句时态有问题，D中that指代很奇怪，但B和E呢，真不知道了，有人说E中结尾的it指代不清，我不太明白这里具体指代什么?
谢谢大家～～～～～～