Betty Is a Single Individual

Betty is a single individual.In 2016,she receives $5,000 of tax-exempt income in addition to her salary and other investment income.Betty's 2016 tax return showed the following information:
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Which of the following statements concerning Betty's tax rates is (are) correct?
I.Betty's average tax rate is 18.7%.
II.Betty's average tax rate is 17.4%.
III.Betty's effective tax rate is 18.7%.
IV.Betty's effective tax rate is 17.4%.
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A) Statements I and III are correct.
B) Statements I and IV are correct.
C) Statements II and III are correct.
D) Statements II and IV are correct.