Sentence Correction (SC) | Geologists in California have discovered a fault

Geologists in California have discovered a fault near the famous San Andreas Fault, one that they believe to be a trigger for major quakes on the San Andreas.

(A) one that they believe to be a trigger for
(B) one they believe to be a trigger for
(C) one that they believe triggers
(D) that they believe to be a trigger for
(E) one they believe acts as a triggerfor

Reason why I believe 'C' iswrong:

While the given sentence says that the fault the Geologists have discovered could be a trigger
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