Why was iron ore considered valuable? Iron Ore is crucial for the manufacture of some of the most important pieces of modern and developing nations alike with applications in bridges, transportation, electronics and most hand tools.

essential for the production of steel

Explanation:

The primary use of iron ore is in the production of iron. Most of the iron produced is then used to make steel. Steel is used to make automobiles, locomotives, ships, beams used in buildings, furniture, paper clips, tools, reinforcing rods for concrete, bicycles, and thousands of other items.

Iron ore is the source of primary iron for the world's iron and steel industries. It is therefore essential for the production of steel, which in turn is essential to maintain a strong industrial base. Almost all (98%) iron ore is used in steelmaking. Iron ore is mined in about 50 countries.

your answer would be (a)