Question

1. Which of the following triggered the Second Industrial Revolution? (Points : 2)
Entrepreneurs figured out how to extract coal much more efficiently.

Geologists discovered vast quantities of petroleum in Germany.

Innovators figured out how to produce steel cheaply.

Engineers developed a much faster steam engine.

Answer 1

If you accept the term '2nd industrial revolution', which not all scholars do, then it was the invention of the Bessemer process for mass producing cheap steel.
So to answer your question directly, it was "Innovators figured out how to produce steel cheaply."

Answer 2

Thank you!

Answer 3

Anytime:)