Required information [The following information applies to the questions displayed below.] Roland had a taxable estate of $16.0 million when he died this year. Required: Calculate the amount of estate tax due (if any) under the following alternatives. (Refer to Exhibit 25-1 and Exhibit 25-2.) (Enter your answers in dollars and not in millions of dollars.) a. Roland's prior taxable gifts consist of a taxable gift of $1 million in 2005. Estate tax due b. Roland's prior taxable gifts consist of a taxable gift of $1.5 million in 2005. Estate tax due c. Roland made a $1 million taxable gift in the year prior to his death. Estate tax due