What Does the "Putting-Out" System of the Nineteenth Century Refer

What does the "putting-out" system of the nineteenth century refer to?

A) Indigent mothers putting newborns "out" to be taken in by orphanages and hospitals
B) The process by which coal was burned to put out heat for steam engines
C) The payment of factory workers according to the amount of goods they produced in a day
D) Workers producing goods at home with raw materials supplied by outside contractors