Final answer:
The subject of this question is History and it is at the High School grade level.
Step-by-step explanation:
This question is asking about a group made up of Americans who opposed the peace treaty between the United States and Spain. This topic falls within the subject of History as it is related to the historical events and conflicts between these two countries. The grade level is High School because it requires knowledge of historical events and concepts.
Learn more about American opposition to the peace treaty between the United States and Spain