Help quick .
Which phrase best completes the diagram?
A sailing ships
B domesticated animals
C steel weapons
D A writing system
![Help quick Which phrase best completes the diagram A sailing ships B domesticated animals C steel weapons D A writing system class=](https://us-static.z-dn.net/files/d5a/37f5f215bbe80a30a98084f21b5cf1ba.png)