Tracy Contracted with Stanley to Pay 2 Installments of $1000

Tracy contracted with Stanley to pay 2 installments of $1000 over a two-month period to buy a new laptop from Stanley.Juan co-signed the note for Tracy.Tracy could not make the second payment on time and Stanley extended the repayment period to three months.Is Juan still responsible as a surety?

A) Yes because sureties never have to consent to a change in a principal's obligation.
B) Yes,because the extension of time was for less than one month.
C) Yes,because if the creditor merely allows the principal more time without the surety's consent,this does not relieve the surety of responsibility.
D) No,because a change was made to the principal's obligation without the consent of the surety.