The correct answer is D) positions in government.
The main spoil of the spoils system is positions in government.
When the winning party in an election need to show its appreciation to the people who helped them during the political campaign, they also have to give something else to them and other close supporters of the party and the candidate such as positions in the government. It is like a reward for their help. So it’s true that the main spoil of the spoils system is positions in government.