For the past three years, Zane has been installing Christmas lights for the New Town Mall. The price had been $500. This year Zane installed the lights but sent the Mall a bill for $600. The Mall sent Zane a check for $500.​
O ​Zane should not allege breach of contract because the contract was for $500 under custom.
O ​Zane should not allege breach of contract because the contract was for $500 under course of performance.
O ​Zane could allege that the Mall had breached its contract by not sending him a check for $600.
O ​Zane should not allege breach of contract because the contract was for $500 under course of dealing.