How does malcolm's army make the witches' prophecy come true?
a. the army searches scotland and finds a man that was not born of a woman's body so that malcolm can defeat macbeth.
b. the army breaks off branches from the trees in birnam wood and carries the branches with them as they march on macbeth's castle.
c. the army sets fire to birnam wood and burns it to the ground, leaving macbeth's castle unprotected.
d. the army finds banquo's son and has him march in front of the army so macbeth can see the future king.