The highest point of tension in Act V of Macbeth is when Macduff reveals that he was not born naturally. He exclaims that he was "from his mother's womb untimely ripp'd" (v.viii) --in modern context that means he was born by c-section. The witches told Macbeth that none of woman-born could harm Macbeth, but that he should fear Macduff. When Macduff reveals this about his birth, Macbeth and the audience know that Macduff is going to be successful in killing Macbeth.
Marginal product is the additional output produces when one more unit of labour is employed. In our case, when Elmo hires a second worker, his marginal product is 7.
