A person pushes a 60 kg grocery cart, initially at rest, across a parking lot. He exerts a pushing force directed 20$^{\circ}$~below the horizontal. If the person pushes the cart with a force of 300 N for 5 m across horizontal ground and then releases the cart, the cart has a speed of 3 m/s. What is the work done by friction during this motion? 
选项为:A:$$-1230J$$  B:$$-1140J$$  C:$$1140J$$  D:$$1230J$$  请回答其中一个选项.