The writings of the Lost Generation were significantly influenced by the Great War, particularly in terms of processing their experiences and the profound sense of loss and disillusionment that followed. While all of the options you provided highlight different perspectives, the most fitting conclusion would be:
They wrote literature in order to process their experiences of being involved in the war.
This option reflects the broader sentiment of the Lost Generation, which included not only those who fought directly in the war but also those who were affected by its aftermath. The war brought about immense changes in societal values, and many writers expressed their disillusionment with pre-war norms and grappling with the trauma of loss, both personally and culturally.
Many Lost Generation authors, such as Ernest Hemingway, F. Scott Fitzgerald, and T.S. Eliot, articulated themes related to the absurdity of war, the alienation from society, and a sense of mourning for the values they felt had been shattered by the war. These themes permeate their works, making it clear that the war's impact was a driving force behind their writing.