Brandon Is the Operator and Owner of a Cleaning Service $\$ 3,000$

Multiple Choice

Brandon is the operator and owner of a cleaning service who uses the cash method of accounting. He receives the following payments on December 31, 2018, the last business day of his tax year:
?
$\$ 3,000$ - Checks received from customers for services rendered during November and December 2018. The checks are deposited in his bank account on January 4, 2019.
$\$ 4,000$ - Checks received from customers for services to be rendered during 2019 . The checks are received in the morning mail and deposited in his bank account on December 31, 2018.
$\$ 2,400$ - A check received from a customer for a service contract. The services under the contract are to be rendered over 24 months, beginning in January 2019. The customer met Brandon at a New Year's Eve party and gives Brandon the check at 11:30 p.m. The check is deposited in his bank account on January 4, 2019.
How much of the $9,400 collected by Brandon on December 31 must be included in his 2018 gross income?

A) $2,400
B) $3,000
C) $5,400
D) $7,000
E) $9,400