Find the inverse of the given relation.

{ (3,1),(3,1),(7,-7),(12,-15) }

A.{ (1,3),(3,1),(-7,7),(12,-15) }
B.{ (1,3),(1,3),(-7,7),(-15,12) }
C.{ (1,3),(1,3),(-7,-7),(-15,12) }
D.{ (1,3),(-1,-3),(-7,7),(-15,12) }