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:
$\begin{array}{ll}\text { Month-by-month payments } & \$ 300 \\\text { One year advance payment } & 3,360 (\$ 280 \text { per month) }\\\text { Two year advance payment } & 6,480(\$ 270 \text {per month) }\end{array}$
If Chicago Cleaning is an accrual basis taxpayer:
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.