还是不懂 GWD8-32

At the annual stockholders meeting, investors heard a presentation on the numerous challenges facing the company, including among them the threat from a rival’s multibillion-dollar patent-infringement suit and the declining sales for the company’s powerful microprocessor chip.

A. including among them the threat from a rival’s multibillion-dollar patentinfringement suit and the declining sales for

B. which includes the threat of a rival’s multibillion-dollar patent-infringement suit and declining sales of

C. included among these the threat from a rival’s multibillion-dollar patentinfringement suit as well as a decline in sales for

D. among them the threat of a rival’s multibillion-dollar patent-infringement suit and the decline in sales of

E. among these the threat from a rival’s multibillion-dollar patent-infringement suit as well as the decline in sales for

答案D

不是很明白这个题........这个D里边到底是跟原来句子是什么关系呢

还有THEM是到底指什么

我选的B,WHICH为什么不可以跳跃修饰呢?