Required information [The following information applies to the questions displayed below.] In 2010 Casey made a taxable gift of $5 million to both Stephanie and Linda (a total of $10 million in taxable gifts). Required: Calculate the amount of gift tax due this year and Casey's unused exemption equivalent under the following alternatives. (Refer to Exhibit 25-1 and Exhibit 25-2.) (Enter your answers in dollars, not millions of dollars. Leave no answer blank. Enter zero if applicable.) O a. This year Casey made a taxable gift of $1 million to Stephanie. Casey is not married, and the 2010 gift was the only other taxable gift he has ever made. Gift tax due $ 0 Unused exemption equivalent b. This year Casey made a taxable gift of $15 million to Stephanie. Casey is not married, and the 2010 gift was the only other taxable gift he has ever made. Gift tax due Unused exemption equivalent c. This year Casey made a gift worth $15 million to Stephanie. Casey is married to Helen in a common-law state, and the 2010 gift was the only other taxable gift he or Helen has ever made. Casey and Helen elect to gift-split. Casey's gift tax due Casey's unused exemption equivalent Helen's gift tax due Helen's unused exemption equivalent