Does the following argument appeal to the Method of Agreement, the Method of Difference, the Joint Method of Agreement and Difference, or Correlation? "Getting the endorsement of the teachers union in this town is absolutely essential to being elected to the school board in this city. No one has ever won a seat on the school board without an endorsement from the teachers union"

a.
Method of Agreement

b.
Joint Method of Agreement and DIfference

c.
Method of Difference

d.
Correlation