Frank Owes an Undisputed Amount to Hanson Gutter Cleaners

Frank owes an undisputed amount to Hanson Gutter Cleaners.Which of the following is true?

A) If Hanson agrees to accept less than the full amount as full payment, the agreement is not binding.
B) The undisputed amount is also known as an unliquidated amount.
C) Payment of less than the full amount will form an accord and satisfaction agreement.
D) If Hanson agrees to accept less than the full amount, the agreement is only binding if it is in writing and signed by Frank.