Which one of the following is not a deduction from the gross estate of a decedent?

a. Unpaid income taxes on income received by the decedent during life.

b. Interest payable on a loan incurred to pay estate taxes.

c. Selling expenses for selling estate property if these sales are necessary to settle the estate.

d. Interest payable after a decedent's death attributable to an installment obligation incurred by decedent.

e. Casualty loss (uninsured) incurred during settlement of the estate.