Jack and Jill are trying to find the slope of a line segment connecting two points, (x1, y1) and (x2, y2). Jack uses the formula m = y2 - y1 x2 - x1 . Jill mistakenly uses a different formula, but still gets the right answer. Which formula COULD she have used? A) x2 - x1 y2 - y1 B) y1 - y2 x1 - x2 C) x1 - x2 y2 - y1 D) y2 - y1 x1 - x2