The correct answer is D) a labor union.
A labor union would be beneficial for the industry's growth.
Labor unions benefit the growth of the industry in that, workers with good jobs, attractive salaries, healthy conditions, and decent working hours, definitely are going to increase the production of the company.
We have the example of Samuel Gompers, the head of the American Federation of Labor (AFL). Samuel Gompers (1850-1924) was an English worker that emigrated to New York City in 1863. In 1886 he was a key figure in the formation of the American Federation of Labor (AFL).