Answer:
B. The invention of the steam engine
Step-by-step explanation:
One of the most important inventions of the Industrial Revolution was the steam engine. With this invention, a new and reliable source of power was available and it significantly improved the production of factories, especially of the textile and the iron industry as well as transportation. However, despite this advance, people had very poor and often dangerous working conditions in factories, they had to work long hours, they were not paid enough (there was no even set a minimum wage), and many of them lived in crowded and unsafe buildings of the city. Certainly, poverty rates did not decrease during this time.