17. If a taxpayer is unmarried they may be eligible to claim Head of Household filing status if they have supported their mother or father, even if he or she did not live with the taxpayer. However: Select one: a. The parent must have been a citizen of the U.S. b. The parent must have been a resident of the U.S. c. The parent must have been a resident of Mexico or Canada d. All of the above are possibilities