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，我选C

不明白最后一个分句是修饰什么的。