The correct option is resolve.

Step-by-Step Explanation:

1. Analyze the sentence structure and context clues:
The sentence begins with a contrasting clause: "Despite his initial hesitation..." This indicates a contrast between his initial feeling of doubt or hesitation and his subsequent actions or attitude, which remained steadfast ("never wavered").

2. Determine the required part of speech and meaning:
The blank space is preceded by the possessive pronoun "Rehman’s" and followed by an infinitive phrase "to contribute...". This means the blank must be filled by a noun that represents a quality or state of mind directed toward achieving a goal, which contrastingly did not waver despite his initial hesitation.

3. Evaluate the given options:
- ambivalence (noun): The state of having mixed feelings or contradictory ideas about something or someone. If he had ambivalence, it would mean he was undecided, which does not fit the idea that his attitude "never wavered."
- satisfaction (noun): Fulfillment of one's wishes, expectations, or needs. "Satisfaction to contribute" is grammatically awkward and does not fit the context of determination overcoming hesitation.
- resolve (noun): Firm determination to do something. "Resolve to contribute" fits perfectly. His firm determination or decision to contribute to the project's success remained strong and steady ("never wavered"), directly contrasting his initial hesitation.
- revolve (verb): To move in a circular orbit around. This is a verb and is grammatically incorrect in this context.

4. Conclusion:
Therefore, "resolve" is the most appropriate word that fits both the grammatical context and the logical flow of the sentence.