The incorect statement is C) For every action there is an equal reaction perpendicular to the direction of the force.
The action and the reaction are both forces. For the object to be in equilibrium, it is necessary that the reaction to be opposite to the action so that their sum is zero (and the acceleration is zero). When the acceleration is nonzero, the reaction is given by the inertia force which is also opposite to the action, and equal to [tex]F=m*a[/tex]
Thus in all cases (zero or nonzero acceleration) the reaction is equal and opposite to the action force.
