The correct answer is b)logos, an appeal based on logic or reason.
Wilson's "War Message to Congress" was one he gave to Congress right before the United States during World War I. In this message, Wilson is justifying why he wanted Congress to declare war on Germany. To do this, Wilson discusses how he discovered that Germany planned on using unrestricted submarine warfare on any ship in the Mediterranean. This would include American merchant ships who were technically neutral in the war at this time.
All of the information mentioned is based on facts and logic. He is not using persuasive language or words that would draw an emotional response. Rather, he is describing the facts of the situation at hand.