An anti$-$modification clause:a$)$ prevents the terms of a contract from being changed by repeated waivers of breaches. b$)$ prevents evidence of prior or contemporaneous agreements which conflict or add to the terms of a written contract.c$)$ specifies the amount of damages in the event of a contractual breach and states that such damages cannot be modified or changed.d$)$ is necessary in a writing to satisfy the statute of frauds.