求助！GWD-18-Q41

At the turn of the twentieth century, forest covering as much as 90 percent of Thailand and accommodating as many as 300,000 elephants, a third of them domesticated and performing various essential tasks.

A.      covering as much as 90 percent of Thailand and accommodating as many as 300,000 elephants, a third of them

B.       covering as much as 90 percent of Thailand accommodated as much as 300,000 elephants, and a third of them were

C.      covered as much as 90 percent of Thailand and accommodated as much as 300,000 elephants, with a third

D.      covered as much as 90 percent of Thailand and accommodated as many as 300,000 elephants, a third of them

E.       covered as much as 90 percent of Thailand and accommodating as many as 300,000 elephants, with a third of them

答案是D，请问是同位语结构吗？那them的指代没有问题吗？

是的,同位语结构.

同位语就近修饰elephants.所以them指代大笨象.

是的,同位语结构.

同位语就近修饰elephants.所以them指代大笨象.

讨论一下哈，我现在又觉得是独立主格结构……