Answer:
ELECTRICITY
Step-by-step explanation:
There were many significant developments and advancements during the 2nd Industrial Revolution. But the one that had the most dynamic and culture-changing impact was the introduction of electrical power. Nicola Tesla has pioneered much of the capability of electricity, and Thomas Edison made it practical with the founding of General Electric as a power company. Electricity revolutionized factories, allowing greater productivity.
Other major developments of the 3nd Industrial Revolution were processes for making steel, which made railways and other building projects much stronger. The automobile was introduced during the 2nd Industrial Revolution also.