Question

as a steel factory owner in the gilded age, how could you use the electric light bulb to grow your business?
by selling electric light bulbs to other factory owners at a higher price to raise revenue
by focusing your business solely on manufacturing light bulbs
by operating your factory more hours each day, increasing output
by reducing the number of employees needed to operate the factory

Explanation:

The electric light bulb allowed factories to operate for more hours. This would increase production (output) as there was more time available for manufacturing. Selling light - bulbs (not the core business of a steel factory) or focusing solely on light - bulb manufacturing would not be in line with the role of a steel factory owner. Reducing employees is not directly related to using the light - bulb.

Answer:

By operating your factory more hours each day, increasing output.