og-57请教大家

57.Affording strategic proximitiy to the Staigt 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 on Algeria was always insecure.

(b)without it their grip on Algeria whould never be secure.

(c)their grip on Algeria was not ever secure if they did not hold it.

(e)never would their grip on Algeria be secure if they did not hold it.

c\e选项的解释说，the pronoun it is ambiguous and could refer to either Morocco or Algeria，同理可证，b选项中的it 也是指代模糊的啊，为什么这里就没问题了啊，请高手指教，谢谢！