Goodness I don't understand this at all!!! I understand finding the coordinates of a parallelogram, but this makes no sense.

So it says "Which of the set of points cannot be the vertices of parallelogram ABCD?"

options are

a) A (-4, -2), B (2, 0), C (3, 3), D (-2, -1)

b) A (-2, -1), B (3, -2), C (4, 1), D (-1, 2)

c) A (0, -2), B (4, -1), C (5, 2), D (0, 5)

d) A (0, -2), B (5, -3), C (7, 1), D (2, 2)

so can someone tell me what formula to use to find the answer? (I'm assuming there's a formula!)