Which of the following was one of the new technologies available under the zhou dynasty?

One of the new technologies available under the Zhou dynasty was iron tools. Prior to this time, tools were made strictly of bronze. Iron was a much better material for tools, as it was more durable. This was just one of the many technological advances that occurred during this time.

If i remember correctly it was caused by people hurling bodies at a country for some reason and them they all became infected