Question

which invention by carl siemens helped make the second industrial revolution possible?

a way to make large quantities of steel in a gas furnace

an internal combustion engine

insulation for telegraph wires

an expanded system of telephones

Explanation:

Carl Siemens developed a regenerative gas - furnace method for making large quantities of steel, which was crucial for the Second Industrial Revolution as steel was a key material for construction, machinery, etc. The internal combustion engine had other key inventors, insulation for telegraph wires and an expanded system of telephones were not his main contributions.

Answer:

a way to make large quantities of steel in a gas furnace