If the system -7x + 7y - 6z = -4, 5x - 3y + 4z = -3, -17x + 13y + hz = k has infinitely many solutions, then k = and h =
a) k = -1, h = -6
b) k = 3, h = 7
c) k = -4, h = 7
d) k = 4, h = -6