What are the three networks of exchange?

the Silk Roads, Indian Ocean, and trans-Saharan

Explanation:

They were the biggest networks for exchanging

the hollywood film industry of 1950 was threatened on several different fronts. television broadcasting was rapidly becoming the dominant entertainment medium in the united states. the paramount anti-trust consent decree requiring separate ownership for production companies and theater chains had gone into effect on 1 january 1950. large numbers of young men and women were marrying, having children, and moving to the suburbs, which affected the viability of downtown first-run movie theaters. foreign revenues were endangered by protectionist tactics including quota systems, high taxes, and blocked funds. finally, the morality and patriotism of hollywood films and filmmakers were under attack from government, religious, and citizens' groups.

explanation:

answer; andrew jackson approved nullification by signing it into law,and john calhoun opposed it saying it was unconstitutional;