Which of the following statements regarding redemption of bonds prior to maturity is true?

a$.$ The call price is negotiated with bondholders at the time of redemption.

b$.$ Non$-$callable bonds can be purchased in the open market by the issuing corporation.

c$.$ Accrued interest is forfeited by the bondholder, per the original bond agreement.

d$.$ Any bond premium or discount remains on the accounting records until the original maturity date.