Step 1: Understand the context of the sentence.
The sentence says: "Despite his initial hesitation, Rehman's ____ never wavered." This indicates that after some hesitation, he still maintained a firm and steady quality that contributed to the project's success.
Step 2: Meaning of the options.
- (A) Ambivalence → Refers to mixed or uncertain feelings. If he had ambivalence, it would mean doubt or indecision, which contradicts "never wavered."
- (B) Satisfaction → Refers to a feeling of contentment, not an inner determination to act. It doesn't fit with the idea of commitment to the project.
- (C) Resolve → Means determination or firmness of purpose. Saying his resolve "never wavered" fits perfectly.
- (D) Revolve → A verb meaning to turn around. Grammatically and logically incorrect in this context.
Step 3: Conclusion.
The correct completion is "resolve," since it conveys determination and matches with "never wavered."
\[
\boxed{\text{Resolve (C)}}
\]