Which of the following requires filing a gift tax return if the transfer exceeds the available annual gift tax exclusion?

a. Medical expenses paid directly to a physician on behalf of an individual unrelated to the donor

b. Tuition paid directly to an accredited university on behalf of an individual unrelated to the donor

c. Payments for college books, supplies, and dormitory fees on behalf of an individual unrelated to the donor

d. Campaign expenses paid to a political organization