April negotiated a 10-year lease with Ajax Corporation to lease her office building. This year, April received $5,000 in rent for the current year and $5,000 in advance rent for the last year of the lease. She also received a $4,000 security deposit, which she will refund at the end of the lease. What amount of rental income must April report this year?

a) $14,000 b) $ 5,000 c) $10,000 d) $ 9,000