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.

1. more research was needed to determine that balloon angioplasty preceded with ultrasound was or was not any better for heart attack patients than
2. more research was needed for determining whether or not balloon angioplasty preceded by ultrasound is any better for heart attack patients than is
3. that more research was needed to determine whether balloon angioplasty preceded by ultrasound is any better for heart attack patients than
4. that more research was needed to determine that balloon angioplasty preceded with ultrasound was any better for heart attack patients than
5. 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

答案给的是B，但是我觉得应该是C吧，请讨论。

好象 gmat里不用 whether or not

我也觉得是C

agree that...but that...