The answer is: 3) Convince citizens to dedicate themselves to the war effort.
Pay attention to this specific part of the excerpt:
But the right is more precious than peace, and we shall fight for the things which we have always carried nearest our hearts
Wilson use those specific wording in order to appeal to the audience's emotion. He want to make the people believe that the threat that imposed by Germany would become a global threat to democracy that provide them with so much freedom compared to other system of government.
If the people can see the correlation between not involved in the war and Germany's chance to eliminate freedom, people became much more likely to support the war effort.