Under a Contract with Soy Farms, Tai Begins Grading a Terraced

Multiple Choice

Under a contract with Soy Farms, Tai begins grading a terraced hillside for planting. Halfway through the project, Tai asks for $5,000 over the contract price, claiming an increase in the "cost of doing business." The farm agrees but later refuses to pay. The agreement to pay more is

A) unenforceable because Tai's performance was a preexisting duty.
B) unenforceable because the farm's promise was illusory.
C) enforceable.
D) unenforceable because Tai's request modified the contract.