Which characteristics will not prove that quadrilateral pqrs, drawn in a coordinate plane, is a parallelogram? a. the slopes and lenghts of pq and rs are equal. b. the slopes of pq and rs are equal, and the slopes of qr and sp are equal. c. the slopes of pq and rs are equal, and the lenghts of qr and sp are equal. d. the lenghts of pq and rs are equal, and the lenghts of qr and sp are equal.