More than any other single factor, increases in the price of

More than any other single factor, increases in the price of imported oil that has been responsible for the inflation experienced by the United States in the last few years.

A) More than any other single factor, increases in the price of imported oil that has been responsible for
- awkward phrasing with the use of 'that'

B) More than any other single factor, increases in the price of imported oil have been responsible for

C) More than any single factor, increases in the price of imported oil have been responsible for

D) Increases in the price of imported oil, more than any other single factor, is the cause of
- 'increases' is plural while 'is' is singular

E) Increases in the price of imported oil, more than any single factor, has been responsible for
- 'increases' is plural while 'has' is singular

Betwen B and D, I'll take D. I feel 'any other' in B is redundant.