What were the effects of the Zhou metal workers mastering iron? Select the two correct answers.
A.
The Zhou conquered the warlords and were the first to unify China.
B.
Iron made stronger, more effective farm tools and increased crop yield.
C.
Iron weapons spread to the masses, contributing to the Warring States period.
D.
The Zhou jealously guarded the secret of smelting the iron and created a trading empire.
E.
Zhou craftman are known for their iron art and it is still sold today.
B. Iron made stronger, more effective farm tools and increased crop yield.
C. Iron weapons spread to the masses, contributing to the Warring States period.