Tell me a joke for brainl

What from the columbian exchange had perhaps the biggest impact on the world?

Why might collective bargaining fail, causing a union to go on strike? a the union agrees with the boss about wages. b the boss compromises about work hours. c the factory goes out of business, causing the workers to lose their jobs. d the boss refuses to address dangerous working conditions in the factories.

Why did china build the great wall of china?