请教一句话中it指代及be of interest to sth何意

该句答案为B。但不太明白 句中的 be of interest to 作何解释？ it 指代什么？照句意似乎该是指 the strait of Gilbraltar.         谢～

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.
(A) if they did not hold it, their grip in 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

LDOCE:

be of (no) interest (to somebody)
(=be interesting or not interesting to someone)
It's a book that will be of interest to a wide range of readers.
What you do in your private life is of no interest to me.
art galleries, museums and other places of interest
topics of general interest (=that everyone wants to know about)

我也认为是：）

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.
(A) if they did not hold it, their grip in 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

我认为it 指的是Morocco,这句话是说：由于摩洛哥战略上接近直布罗陀海峡，法国人在整个十二世纪上半页都对它（摩洛哥）很感兴趣，因为法国人认为如果不能控制摩洛哥，他们对阿尔及利亚的控制将得不到保障。

对对，你理解正确，我错了：）

明白了   they, their 指的都是 the french, it 指Morocco  谢谢各位