Which of the following accrued liabilties would most likely NOT be considered "uncertain"?

a) An accrued liability relating to a recall for a defect in the design of an automobile airbag, the fix for which has not yet been approved by regulators

b) An accrued liability relating employee medical insurance premiums

c) An accrued liability relating to closing three plants in Italy and laying off 400 workers

d) An accrued liability related to alleged violations of the Clean Air Act which are being investigated by federal authorities and which managment belives have more likley than not occured