Describe one similarity between the commercial interactions in the regions mentioned in the passage and commercial interactions along the overland Silk Roads in the period circa 1200–1450.

The following passage describes an example of __negative externality in the 1980s, manufacturing power plants in the midwest burned coal with high sulfur content, which when released as smoke, mixed with moisture in the atmosphere to create an acid that blew into canada and new england. the acid fell to the earth in the form of rain, killing fish and causing deforestation and building deterioration.