They provided silk
Hope this helped
Answer:
<u><em>Gravity </em></u>
Explanation:
Basically, the sun keeps all the planets in the orbital motion by gravitational alignment. Just as the earth and moon have a similar gravitational pull towards each other. Galileo gave the idea of Copernicus theory. The theory also follows the models of the geocentric model of Ptolemy. Stars are at a fixed position from the sun and far away from the sun. As compared to the earth which is nearby and rotates on its axis from right to left.
I think that PROCESSING is an example of secondary econmic
