请教一道GWD语法

cx89916

GWD T-4-Q16
Humans have been damaging the environment for centuries by overcutting trees and farming too intensively, and though some protective measures, like the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great increases in population and in the intensity of industrialization are causing a worldwide ecological crisis.

A.    though some protective measures, like the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great increases in population
B.    though some protective measures, such as the establishment of national forests and wildlife sanctuaries, were taken decades ago, great increases in population
C.    though some protective measures, such as establishing national forests and wildlife sanctuaries having been taken decades ago, great population increases
D.    with some protective measures, like establishing national forests and wildlife sanctuaries that were taken decades ago, great increases in population
E.    with some protective measures, such as the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great population increases

正确答案为B，想问一下，and应该是连接两个主句，而这个是连接了一个主句和一个though从句，还是说它其实连接的是两个主句human。。。和great increase。。。
谢谢

qizhi77

连接2个主句

cx89916

谢谢~