I need help coming up with a research question

I have to write an extended essay . I choose World War 2 because my great grandfather was a polish soldier in the war. My first research question was to what extend did the world war cause PTSD within combat vets? But my teacher said that was obvious and i need an argumentative research question. My great grandfather was captured by the soviets and taken to a concentration camp where he escaped. He had severe PTSD after the war and screamed at night and what not. So I want to write about him but i need an argumentative topic