prep的一道语法

Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil, their descendants, popularly known as killer bees, had migrated as far north as southern Texas.

(A) Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil,

(B) In less than 35 years since releasing African honeybees outside Sao Paulo, Brazil,

(C) In less than the 35 years since African honeybees had been released outside Sao Paulo, Brazil,

(D) It took less than 35 years from the release of African honeybees outside Sao Paulo, Brazil, when

(E) It took less than the 35 years after the time that African honeybees were released outside Sao Paulo, Brazil, and then

answer is A, i chose B

if A is right, what is the function of "less than ...., Brazil"

B. releasing 动作的主语语法上，是主句的主语 their descendants，但是逻辑上就错了。

A."less than ...., Brazil":为状语

主句题干阅读是： their descendants……had migrated……less than 35years after ……

up up.

请NN们帮帮忙啊！

Less than 35 years after the release of ..., 主语 had migrated ...

怎么时态看起来怪怪的？