Final answer:
The correct answer is option c) The success of the electric industry.
Step-by-step explanation:
The moment that allowed J.P. Morgan to invest as he wished was not solely defined by a single event, but by a series of developments that established him as a leading financier. With the creation of Thomas Edison's incandescent light bulb and the eventual formation of Edison General Electric Company, backed financially largely by Morgan himself, a solid foundation was laid that reinforced his influence in the industry.
The success and expansion of the electric industry cannot be attributed to the stock market crash of 1929, the creation of the electric chair, or the invention of the light bulb alone, but rather a combination of Morgan's strategic investment decisions and the burgeoning industrial developments. J.P. Morgan's financing and support of Edison's endeavors, as well as his role in guiding subsequent mergers, underscored the success of the electric industry which enabled him to invest freely in companies like General Electric without parental restraint.