special assessment debt should be reported on the balance sheet of a city if the debt is to be paid from assessments on property owners and :

a) the city has guaranteed payment of the debt and the probability of the city having to make good on the guarantee is 50 percent or greater.

b) The city has guaranteed payment of the debt but the probabaility of the city having to make good on the guarantee is remote

c) the city has no legal responsibility for the debt, but in the past has made up any property owner default

d) all of the above