People realized iron ore mixed with coal made a stronger metal
Answer: Option B
Step-by-step explanation:
The three famous ages were the stone age, the bronze age and the iron age. There was shift from the bronze age to the iron age because people thought that even though wrought iron was not that strong but they thought that mixing iron with a very little amount of coal which is approximately only 2% would make iron as strong as steel and making weapons from such a strong metal would be very strong to use and effective also and is a better alternative compared to bronze. So this replaced bronze with iron.