Which of the following is not a condition for a contingent liability to exist?

Which of the following is not a condition for a contingent liability to exist?

a. There is a potential future payment to an outside party that would result from a current condition.
b. There is uncertainty about the amount of the future payment.
c. The outcome of an uncertainty will be resolved by some future event.
d. The amount of the future payment is reasonably estimable.