Answer:
A) not cancel the contract.
Step-by-step explanation:
If Delicioso Deli agreed to the price increase, then they cannot cancel the contract unilaterally. Coffee Roasters must prove that Delicioso Deli agreed to the new price either by signing an addendum to the original contract or by agreeing to do so by email. If it was done orally, then Coffee Roasters must provide proof of it, i.e. they recorded the conversation.
Contracts can be changed if the market conditions change, but the changes must be agreed by both parties.