Which sentence best relates an example in an objective manner?

industry needed to reach a broad market for its desirable products.
it was amazing that farmers in the northwest territory could produce such large crops.
two large canal systems linked eastern manufacturers with the northwest territory.
the railways ran through the beautiful scenery of the great lakes and rolling farmlands.

The sentence best relates an example in an objective manner is Two large canal systems linked Eastern manufacturers with the Northwest Territory.

Objective manner means to present facts as they are without undue influence from the speaker or author. 

The bolded words make the sentence subjective:
Industry needed to reach a broad market for its desirable products.
It was amazing that farmers in the Northwest Territory could produce such large crops.
The railways ran through the beautiful scenery of the Great Lakes and rolling farmlands.

Democracy and darwinism would be my answer.