Sentence Correction

At the annual stakeholders 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 patent infringement suit and the declining sales for
B: Which includes threat of a rival's multibillion dollar patent infringement suit and declining sales of
C: inlcuded among these the threat from a rival's multibillion dollar patent infringement suit as well as decline in sales for
D: among them the threat of a rival's multibillion dollar patent infringement suit and decline in sales of
E: among these the threat from rival's multibillion dollar patent infringement suit as well as the decline in sales for
[spoiler]
the answer is D and i am not convinced with the answer because its not parallel, i think the answer should be E. how do you guys think?[/spoiler]

"sales of " is correct idiom

Between B and D ,B is out because "which" after comma wrongly modifies company.

D is better. Of coz not the best. Select D and move on.

There is also Parallelism going on here.

"The threat" needs to match with "the decline." Only D and E does this.