Rearrange the parts of the sentence in correct order.
The party faithful, who
P-expectations, are now disillusioned
Q-had greeted his political arrival in 2004
R-with great enthusiasm, and

The correct option is B.
The relative pronoun "who" requires a predicate describing the actions of "The party faithful". Part Q ("had greeted his political arrival in 2004") fulfills this.

Greeting someone's arrival is naturally followed by the manner in which they were greeted, which is found in part R ("with great enthusiasm, and").

The conjunction "and" links the initial past state to the current status in part P ("expectations, are now disillusioned"). Here, "enthusiasm and expectations" works collectively to clarify their initial feelings before being disillusioned.

Therefore, the correct arrangement is Q-R-P.