货币是经济运行的血液，它在经济生活中扮演着重要的角色。关于货币的产生，下列说法正确的是[ ]

A、货币是固定地充当一般等价物的商品

B、纸币是价值符号

C、货币是商品交换长期发展的产物

D、货币的本质是一般等价物

He went __________ his way __________ some flowers for his mother.[ ]

A. out of, to buy

B. out, to buy

C. out of, buying

D. out, buying