Billy Dent, as the owner of an apartment building, receives and makes the following payments during 2009: Received in January 2009 rent that was due in December 2008-----$5,000 Received in December 2009 rent not due until January...$4,000 Security deposit which is to be refunded when tenant vacates the apartment.....$500 How much rental income must Billy Dent include on his 2009 income tax return