Which of the following would best benefit the development of niche marketing?

[Manal]

A. a decline in the cost of advertising on radio and newspapers enabling firms to more efficiently reach a wide audience
B. a Supreme Court ruling that limits the market share individual firms in a market are allowed to serve
C. a growing acceptance of free trade agreements such as NAFTA
D. a manufacturing improvement enabling firms to more efficiently design and produce specialized products for small groups of consumers