一道关于平行的题~

qhdwxy

In Egypt in the late Paleolithic period，the climate changed，pastures became deserts，and the【 inhabitants were forced to withdraw to the land bordering the Nile from their hunting grounds.   】

（A）inhabitants were forced to withdraw to the land bordering the Nile from their hunting grounds
（B）inhabitants had been forced to withdraw from their hunting grounds to the land that bordered the Nile
（C）inhabitants were forced to withdraw from their hunting grounds to the land bordering the Nile
（D）inhabitants having been forced to ，withdraw from their hunting grounds to the land that bordered the Nile
（E）inhabitants withdrew，because they were forced to，from their hunting grounds to the land bordering the Nile

选C~
能排除BD选项，然后就。。。。求大神指教~谢谢！