Pursuant to Coreys will, Emma (Coreys sister) inherits his property. Emma dies in a later tax year. The estate tax attributable to the inclusion of the property in Coreys gross estate was $300,000. The estate tax attributable to the inclusion of the property in Emmas gross estate is $400,000. Emmas credit for the tax on prior transfers is:

a. $0 if Emma died nine and one-half years after Corey.

b. $300,000 if Emma died three years after Corey.

c. $400,000 if Emma died one year after Corey.

d. $180,000 if Emma died five and one-half years after Corey.