Peterson Kurth & Hastings LLP represented Jasper Liu in the purchase of real estate in Bel Air, California. Jasper received an invoice for $2,500 for the legal services performed by the law firm. The $2,500 is money owed for which a bill has been sent but a payment has not yet been received. This is called: 

accounts receivable 

accounts payable 

cash basis accounting 

accrual accounting