Final answer:
The most suitable category to compare Hemingway's 'In Another Country' and Crane's 'The Little Regiment' is theme, with setting also playing a significant role in influencing the narratives.
Step-by-step explanation:
To compare Ernest Hemingway's In Another Country and Stephen Crane's The Little Regiment, the most suitable category would be theme. Both works delve into the experiences of war, trauma, and the struggle of individuals within this context. Meanwhile, setting also plays a critical role in these works, as it provides the backdrop against which the characters' experiences unfold and can greatly influence the overall theme of the narrative. Although symbolism and allusion might also be present, they are typically elements that support rather than define the primary comparison between these two stories.