Answer:
B. a sea of peace or a new terrifying theater of war
Explanation:
Pathos is on of three main rhetoric devices or persuasive tools, other two being ethos and logos.
It should be easy to remember, because the adjective pathetic was derived from it, meaning something that evokes the sentiment of sorrow, sadness or pity.
In broader sense, pathos is used to touch us using any emotion. In this case, there is a choice between see of peace or theater of war.
That basicallu means that there is a choice between a serenity and prosperity, on one side, and fear and brutality on another.
Being presented with such choice, people will always chose the first option. This means that this emotional appeal persuaded people to make a decision.