Which situation would be more likely to occur in the modern era than in earlier periods of human history?

Struggles in farms happen today and happened in the past as well, but they were most likely to happen in the past without the tools of our age. And violence has also been used as a way to obtain power since humans exist.

A factory creates a health hazard in the surrounding community by polluting the river.

Divisions in communities have happened since humans are humans. Struggles in farms happen today and happened in the past as well, but they were most likely to happen in the past without the tools of our age. And violence has also been used as a way to obtain power since humans exist. But factories, on the other hand, were not present during our early years as a species. In fact, we lived thousands of years in relatively developed civilizations before we have made the first factory.

4 copper and gold, the california gold rush is why im pretty sure.