Sentence Correction

The increase in unemployment rates, coupled with significantly increased retail prices as well as energy costs, are forcing many homeowners to look into alternative sources of fuel in order to save money on winter heating.

A] unemployment rates, coupled with significantly increased retail prices as well as energy costs, are

B] rates of unemployment, coupled with significant increases in retail prices and energy costs, have been

C] unemployment rates, coupled with significant increases in both retail prices and energy costs, is

D] unemployment rates, coupled with significantly increased retail prices as well as energy costs, is

E] rates of unemployment, coupled with significant increases in both retail as well as energy costs, had been

[spoiler]
The OA is C.[/spoiler]

Got the OA as C. But only had doubts on the option D.

According to me the option D is incorrect because it is not parallel as compared to the other part of the sentence.

'The increase in unemployment rates' compared to 'coupled with significantly increased retail prices as well as energy costs' is not parallel as in something is not parallel to increased something.

That is why option C is the correct answer.

Also 'coupled with significantly increased retail prices as well as energy costs' is a modifier and so the question is Can parellelism parameter be applied to compare the subject with its own modifier.

Also please see any other error in option D as compared to the option C.

I found this error and that is why posted this question...