Answer:
the Hadean (4600–4000 Ma), Archean (4000-2500 Ma) and Proterozoic (2500-541 Ma).
Explanation:
It was the Cotton gin it made things easier and faster.
Astronomers could use radio telescopes to accurately map the positions of these O and B stars and use the Doppler shifts of the radio spectrum to determine their rates of motion. When they did this with many stars, they were able to produce combined radio and optical maps of the Milky Way's spiral arms.
Answer:
D. to create cultural unity during the Song Dynasty.
Explanation:
Foot binding began in the Song dynasty and became a shorthand for ethnic pride.
Democracy is the answer hope this helps
