[单选题]
Action-reaction forc s9zwm,*/ qre; ppfgs8u;igc g7-e a;h)nc*3 l.tl5 y6jxgsdro4fkh3 es are
A. equal in magnitude and point in the same direction.
B. equal in magnitude but point in opposite directions.
C. unequal in magnitude but point in the same direction.
D. unequal in magnitude and point in opposite directions
