On August 1, Metro Inc. leased a luxury apartment unit to Klum. The parties signed a one-year lease, beginning September 1, for a $1,000 monthly rent payable on the first day of the month. The normal lease term for this property is three years. At the August 1 signing date, Metro collected $540 as a nonrefundable fee for allowing Klum to sign a one-year lease, and $1,000 rent for September. Klum has made timely payments each month, but prepaid January's rent on December 20. In Metro's income statement for the year ended December 31, rent revenue should be reported as:

$4,000

$4,180

$4,540

$5,180