GMAT Sentence Correction (SC) | No analyst can ever be completely sure whether the value of

No analyst can ever be completely sure whether the value of a share will rise or not.

a. whether the value of a share will rise or not
b. if the value of a share will rise
c. whether or not the value of a share will rise
d. about whether a share's value will rise or not
e. whether a share's value will rise


Plz provide explanation for your choice!

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