During World War II$,$ the U$.$S$.$ military used plastics in weapons and motor vehicles. Following the war, plastics manufacturers began to produce products that consumers could use in their homes. This is most closely related to which step in Schumpeter's progression for finding new business opportunities?

a$.$ Develop a new market for an existing product.

b$.$ Use new technology to produce a new product.

c$.$ plastication

d$.$ Use existir.y technology to produce an old product in a new way.