Debt is a contractual obligation that: (a) requires a repayment of a stated amount and interest over the period, (b) Both requires the payout of residual flows to the holders of these instruments and requires a repayment of a stated amount and interest over the period, (c) allows the bondholders to sue the firm if it defaults, (d) Both requires a repayment of a stated amount and interest over the period; and allows the bondholders to sue the firm if it defaults, or (e) requires the payout of residual flows to the holders of these instruments.