Knowing That in the Real World, the Demand for Goods

Knowing that in the real world, the demand for goods and services could change unexpectedly, firms would attempt to deal with it by:

A) producing different levels of goods and services according to the changes in demand.
B) switching to the production of another product in the short-run.
C) maintaining an inventory.
D) closing down the production in the short-run with the hope that the situation would change in the future.