The Mythical Country of Januvia Imposes a Tax Based on the Number

The mythical country of Januvia imposes a tax based on the number of titanium coins each taxpayer owns at the end of each year per the following schedule:
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Marvin,a resident of Januvia,owns 300 titanium coins at the end of the current year.
I.Marvin's titanium coins tax is $2,800.
II.Marvin's marginal tax rate is $6.
III.Marvin's average tax rate is $9.33.
IV.Marvin's average tax rate is $6.

A) Statements II and III are correct.
B) Statements I, II, and IV are correct.
C) Statements II and IV are correct.
D) Statements I, II and III are correct.
E) Only statement II is correct.