With Respect to Income from Services, Which of the Following

With respect to income from services, which of the following is true?

A) The income is always amortized over the period the services will be rendered by an accrual basis taxpayer.
B) A cash basis taxpayer can spread the income from a 24-month service contract over the contract period.
C) If an accrual basis taxpayer sells a 36-month service contract on July 1, 2017 for $3,600, the taxpayer's 2017 gross income from the contract is $600.
D) If an accrual basis taxpayer sells a 24-month service contract on July 1, 2017, one-half (12/24) the income is recognized in 2018.
E) None of these.