The sentence in Richard Connell's "The Most Dangerous Game" that suggests of Sanger Rainsford's time serving in the war would be the excerpt <span>"Rainsford had dug himself in in France when a second's delay meant death."
The mentioned sentence talks about a life-or-death situation wherein Rainsford needed to dug himself or else he will be killed. This situation suggests an imminent danger and therefore hints at a war. </span>
Based on that passage, I'd say the young man is active because he's jogging, and friendly he smiled in encouragement to elderly men. Nothing in the passage indicates that he is either intelligent or snobbish.