William, a Landlord, Wishes to Buy Melanie's Eighth Floor Apartment

William, a landlord, wishes to buy Melanie's eighth floor apartment in central London. The apartment is worth a hefty sum and Melanie, an elderly widow, has fallen into serious debt and is looking to sell. William offers a fair price for the apartment, but Melanie refuses it, thinking she can get more. William tells Melanie that, if she does not accept the sum, he'll send some rogues to beat up her nephew and evict him out of his apartment on the first floor. Melanie agrees to sell for the sum offered by William. If Melanie wishes to avoid the contract for duress, what must she show?

A) That the threat was a reason for her decision to contract.
B) That the threat was a significant reason for her decision to contract.
C) That the threat was the reason for her decision to contract.