The correct answer is - D. how to make iron.
The Zhou dynasty was one of the greatest dynasties of China, and among many achievements of their reign, the artisans of this dynasty managed to learn how to make iron. This was revolutionary for the Chinese people, and it was of great use in the agriculture after the tools for it started to come in iron version, and it made everything much easier, quicker, and more efficient.
D. The Grand canyon's layers get older from bottom to top
The deeper you go, the older the layer
The information found by Lewis and Clark showed many new places to settle, what the new land was like, and what could be accomplished in those areas. They found more land to farm and build homes. They also found some of the major rivers and landmarks of today.
