Identify which of the following statements is true. Options: a) A nonresident alien from a nontreaty country is taxed at a 35% rate on U.S. source investment income without the benefit of any deductions. b) Capital gains earned in the United States, other than in the conduct of a U.S. trade or business, are taxed to a nonresident alien only if the alien is physically present in the United States for at least 183 days during the tax year. c) Aliens, who are U.S. residents, are taxed only on their U. S. income. d) All of the above are true.