Which of the Following Is Correct with Respect to Input

Which of the following is correct with respect to input and output markets?

A) In the input market,firms supply good and services in response to demand on the part of households.
B) In the output market,firms buy resources from households,which then supply those resources.
C) Consumer buying patterns provide information that helps companies decide which products to produce.
D) Consumers are restricted in the companies they can work for.
E) Input and output markets exist only in communist countries.