Which of the following sentences is INCORRECT？（2012)A．Poultry are very expensive in the ci

Which of the following sentences is INCORRECT？(2012)

A．Poultry are very expensive in the city.

B．New machinery were introduced in the factory.

C．The police are investigating the murder case.

D．The militia were called out to rescue flood victims.

请帮忙给出正确答案和分析，谢谢！