Answer:
The words "valiant fight" help create an admiring tone.
Step-by-step explanation:
This is the most accurate statement that describes how the language of the sentence affects its tone. In this passage, the author explains how Pittsburgh's refineries had to get rates on their oil which would enable them to run independently. However, this assertion is described in a tone of admiration by the author. He describes their attitude as "valiant" and their conflict as a "fight." This shows that the author believes the actions to have been necessary and admirable.