The marketing concept that starts with a well-defined market, focuses on customer needs, and integrates all the marketing activities that affect customers takes a(n) .

Bella can produce either a combination of 60 silk roses and 80 silk leaves or a combination of 70 silk roses and 55 silk leaves. if she now produces 60 silk roses and 80 silk leaves, what is the opportunity cost of producing an additional 10 silk roses?