Idle Contractor Corporation begins constructing a building for Haute Apartments, Inc. In mid$-$project, Idle asks for $$150,000$ more, claiming an increase in ordinary business expenses. Haute agrees. This agreement is

Group of answer choices

enforceable as an accord and satisfaction.

unenforceable due to the preexisting duty rule.

unenforceable as an illusory promise.

enforceable because of unforeseen difficulties.