What do biologists believe is to blame for the decrease in the amount of fish in the Columbia River? Question 3 options:

Pollution, a breach, and spawning

Fish hatcheries, fish ladders, and fishing

Fish hatcheries, pollution, and dams

Dams, a breach, and pollution

How was rockefeller able to build his monopoly across the oil industry? he found newer and cheaper ways to refine oil, increasing his profits. he confined his business to ohio so he could buy all the refineries there. he bought up oil refineries, cut costs, and reinvested his profits in other refineries. he began to sell kerosene as well as oil, expanding his market.

How did the new working class of the industrial revolution differ from the working classes of the earlier, farm based economy?

Before the civil war, the constitution protected slavery -true -false