For this assignment, as with all assignments, I recommend that you choose the theory you are most comfortable with and understand the best. You instructor is probably looking for you to pick a topic and apply the theory you think works the best to explain your topic and then offer a comparison with the other theories as a means to support your point. Before you begin you should choose a topic and determine what theory you are using. Revisit your course materials and notes to help you decide and to find things that will support you points.
Remember that functionalism and conflict theory are both macro level theories. I'm going to talk about war broadly as a social problem for sake of discussion. Please bear in mind that this is a very broad topic so I recommend finding something more focused for your assignment.
Functionalism is the first main body of theory in sociology and some of the theorists who fit this category are Comte (the 'father' of sociology), Durkheim (anomie, organic and mechanical solidarity, he ...
The three main 'classical' bodies of theory in sociology, functionalism, conflict theory, and symbolic interactionism are explained and then briefly applied to understanding war and society.