求助！！

小新和小白9899

At the time of the Mexican agrarian revolution, the most radical faction, that of Zapata and his followers, proposed a return to communal ownership of land, to what had been a pre-Columbian form of ownership respected by the Spaniards.(A) land, to what had been a pre-Columbian form of ownership respected by the Spaniards
(B) land, a form of ownership of the pre-Columbians and respected by the Spaniards
(C) land, respected by the Spaniards and a pre-Columbian form of ownership
(D) land in which a pre-Columbian form of ownership was respected by the Spaniards
(E) land that had been a pre-Columbian form of ownership respected by the Spaniards
这道题答案是A。我参考了CD之前的关于这道题的帖子，明白这里面what是指代communal ownership of land，最后面to what...实际上是同位语从句。但是我想请问下为什么这里面要用what作为一个这么奇怪的同位语结构呢？还有E选项错误是不是在于THAT可能就近指代land了，而不是communal ownership of land了啊，求NN帮助