Which set of vertices forms a parallelogram?

a(2,4), b(3, 3), c(6, 4), d(5, 6)

a(-1, 1), b(2, 2), c(5, 1), d(4, 1)

a(-5, -2), b(-3, 3), c(3, 5), d(1, 0)

a(-1, 2), b(1, 3), c(5, 3), d(1, 1)

For a set of vertices to form a parallelogram, the opposite sides must be equal in length and slope. The length can be calculated using the distance formula and slope using the slope formula. Among the choices, the answer is
A(2,4), B(3, 3), C(6, 4), D(5, 6)