The correct answer is D. Party organizers, volunteers, voters, and elected officials.
Step-by-step explanation
The text describes the four main phases for the election of a senator from Mississippi who manages to be elected through the efforts of all the groups that make up his party. Initially the Party organizers "work on strategies to build the candidate's profile and raise funds on his behalf." In second place the volunteers "donate their time by going door to door and speaking to citizens across the state". Third, voters "turn out in record numbers to vote for the candidate." Finally, the new senator (elected officials) thanks party members for their efforts. According to the above, the correct answer is D. Party organizers, volunteers, voters, and elected officials.