darlene runs a fruit and vegetable stand in a medium- sized community where there are many such stands. her weekly total revenue equals $ 2,000. her weekly total cost of running the stand equals $ 3500 consiting of $ 2500 of variable costs and $ 1000 of fixed costs an economic woulf like advice darlene to a) shut down as quickly as possible in order to kinimize her losses b) keep the stand open because it is generating economic profit c) keep the stand open for a while longer because she is covering all her varibale costs and some of her fixed costs d) keep the stand open for a while longer because she is covering all her fixed cosrs and some of her variable costs