[Solved] Which of the following phases of new-product development is likely the most cost-effective procedure? A) Commercialization B) Concept testing C) Business analysis D) Product development E) Test marketing Adolescents: Young people in the transitional stage of physical and psychological development that generally occurs during the period from puberty to legal adulthood. Precocious Puberty: The onset of puberty occurring at an unusually early age, often defined as before 8 in girls and before 9 in boys. Sexual Activity: Behaviors associated with the expression of sexuality and erotic desire, including intercourse and other forms of physical intimacy between individuals. Adolescence: The transitional stage of physical and psychological development that generally occurs during the period from puberty to legal adulthood.