What differentiates a spoiling attack from a counterattack?
a. A spoiling attack seriously impairs a hostile attack while the enemy is still forming or assembling for an attack.
b. A spoiling attack cuts off or destroys enemy advance units after the enemy's attack has commenced.
c. A spoiling attack spoils the enemy's gains and decisions after the attack has commenced.
d. A counterattack strikes the enemy before they are able to assemble or form for an attack.