请教一道语法（关于will had done的用法）kaplan

San Franciseans of the 1890’s mocked the claim that declared Los Angeles a world city, yet within twenty years a powerful municipal will had made this boast a reality.

A  yet within twenty years a powerful municipal will had made this boast a reality.

B  yet within twenty years a powerful municipal will made this boast a reality.

C  yet a powerful municipal within twenty years will make this boast a reality.

D  yet this boast had become a reality within twenty years because of a powerful will municipally.

E  yet within twenty years a minicipal will had made this boast a powerful reality.

答案A

这里的will had done 的用法是什么意思啊？

实在是不明白