Which of the following is the minimum limitation necessary for filing an involuntary bankruptcy petition in connection with a company that has 57 unsecured creditors?

a. The signature of 12 creditors to whom the debtor owes at least $14,775 in unsecured debt

b. The signature of six creditors to whom the debtor owes at least $18,250 in unsecured debt

c. The signature of three creditors to whom the debtor owes at least $16,750 in unsecured debt

d. The signature of nine creditors to whom the debtor owes at least $23,225 in unsecured debt