what law made it clear that people in the north free states were expected to cooperate if southern owners tried to reclaim a slave that had excepted in the north

Explanation:

t required that all escaped slaves, upon capture, be returned to their masters and that officials and citizens of free states had to cooperate.

...

Fugitive Slave Act of 1850.

Citations

Public lawPub.L. 31–60

Statutes at Large9 Stat. 462

Legislative history

Signed into law by President Millard Fillmore on September 18, 1850

B. The author is biased against a law because it would financially  affect his business.

Explanation:

The author of the excerpt is biased. He treats environmental protection laws as if it were a strategy for politicians to end his business. Environmental laws are meant to protect the environment so that we have a comfortable life, but the author of the excerpt only cares about his company's profit and acts as if environmental laws were a bad, selfish thing.

The part of the excerpt that makes this clear is "By limiting the amount of chemicals I can pour into the local river, these politicians are trying to  drive down our productivity and put me out of business!"