After spending years developing and testing a new MP$3$ player, Musique, Inc. has finally launched its new product in the market. The company has assigned its best marketing managers to handle the launch. It has also employed an extensive marketing campaign with ads in television, newspapers, and billboards. Which of the following stages of the product development process is Musique currently in$?$

Group of answer choices

a$.$ Concept testing

b$.$ Product development

c$.$ Test marketing

d$.$ Commercialization