In relation to the law of agency, explain the circumstances in which a principal may be bound by a contract entered into by an agent on his behalf without his express authority. (10 marks)

以下最能体现“ * * ”时期的文艺方向的是(　　)

A．“文艺为人民服务，为社会主义服务”

B．“弘扬主旋律，提倡多样化”

C．“百花齐放，百家争鸣”

D．“办好样板戏，服务工农兵”