Which choice is the common difference between the terms of this arithmetic sequence?4x + 7y, 8x + 2y, 12x + -3y, 16x - 8y, 20x - 13y, ...
A.4x - 5y
B.-5x - 4y
C.4x + 5y
D.5x + 4y
E.5x - 4y