Which of the Following Statement Is/are Included in Adam Smith's

Which of the following statement is/are included in Adam Smith's four requirements for a good tax system?
I.Changes in the tax law should be made as needed to raise revenue and for proper administration.
II.A tax should be imposed in proportion to a taxpayer's ability to pay.
III.A taxpayer should be required to pay a tax when it is most likely to be convenient for the taxpayer to make the payment.
IV.The government must collect taxes equal to it's expenses.

A) Statements I and II are correct.
B) Statements I and IV are correct.
C) Statements II and III are correct.
D) Statements II and IV are correct.
E) Statements III and IV are correct.