Suppose that the social choice procedure being used is sequential pairwise voting with a fixed agenda, and that you have agenda-setting power (that is, you get to choose the order). What order should you choose if you want alternative a to be the social choice?

This question is incomplete; here's the complete question.

Suppose that we have three voters and four alternatives, and suppose the individual preference lists are as follows:

Voter 1: a b c d

Voter 2: c a b d

Voter 3: b d c a

Suppose that the social choice procedure being used is sequential pairwise voting with a fixed agenda, and that you have agenda-setting power (that is, you get to choose the order). What order should you choose if you want alternative a to be the social choice?

Answer: c vs. d, then winner vs. b, then winner vs. a

Explanation:

In a Sequential Pairwise Voting, the winner may depend on the order in which the elections are carried, so having agenda-setting power and knowing individual preferences allows us to assure a specific outcome for the social choice.

If we begin with the election of Alternative C vs. Alternative D, voters 1 and 2 will provide enough votes for Alternative C to win.

Next, Alternative C being the winner, goes to election vs. Alternative B, and voters 1 and 3 provide enough votes for Alternative B to win.

Finally, Alternative B being the winner goes to election vs. Alternative A, and voters 1 and 2 provide enough votes for Alternative A to win.