Fact Pattern 10 - 3 Best Restoration, Inc

Multiple Choice

Fact Pattern 10 - 3 Best Restoration, Inc., begins renovating houses for City Edge Property Company under a contract for a stated amount per house. After six months, Best demands an extra $20,000 per house. City Edge agrees to pay.
Refer to Fact Pattern 10 - 3. Suppose Best offers no reason for the extra $20,000, but asserts that it will stop work if it is not paid. The agreement is

A) enforceable as the consideration is past.
B) enforceable due to unforeseen difficulties.
C) unenforceable as an illusory promise.
D) unenforceable due to the preexisting duty rule.