Chicago Cleaning Services Provides Nightly Janitorial Services at a Monthly

Chicago Cleaning Services provides nightly janitorial services at a monthly rate of $300. Customers have three payment options:
If Chicago Cleaning is an accrual basis taxpayer:
$\begin{array}{lr}\text { Month-by-month payments } & \$ 300 \\\text { One year advance payment } & 3,360(\$ 280 \text { per month }) \\\text { Two year advance payment } & 6,480(\$ 270 \text { per month }) \end{array}$

I.All cash payments are taxable when they are received.
II.One-year advance payments must be included in income in the year they are received.
III.Two-year advance payments attributable to service in two years; hence, must be included in income in the year they are received.
IV.One-year advance payments may be deferred: $280 would be included in income for each month of service provided.
?

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