Sentence Correction

Researchers agreed that the study of new treatments for heart attack patients was
extremely important but more research was needed to determine that balloon angioplasty
preceded with ultrasound was or was not any better for heart attack patients than the
balloon procedure by itself.
A. more research was needed to determine that balloon angioplasty preceded with
ultrasound was or was not any better for heart attack patients than
B. more research was needed for determining whether or not balloon angioplasty
preceded by ultrasound is any better for heart attack patients than is
C. that more research was needed to determine whether balloon angioplasty preceded
by ultrasound is any better for heart attack patients than
D. that more research was needed to determine that balloon angioplasty preceded
with ultrasound was any better for heart attack patients than
E. that more research was needed for determining that balloon angioplasty preceded
by ultrasound is or is not any better for heart attack patients than is

I think it is C...

IMO C

to determine is correct as compared to "for determining"

also whether or not is not correct

whether should be preferred

THUS C

OA is given as B. But I think it should be C. OA is not reliable in sets.