Which common literary theme or conflict appears in this passage?

a) man vs. self b) man vs. nature c) man vs. society d) man vs. the gods

passage: when the general, nursing his bruised shoulder, had gone, rainsford took up his flight again. it was flight now, a desperate, hopeless flight, that carried him on for some hours. dusk came, then darkness, and still he pressed on. the ground grew softer under his moccasins; the vegetation grew ranker, denser; insects bit him savagely. then, as he stepped forward, his foot sank into the ooze. he tried to wrench it back, but the muck sucked viciously at his foot as if it were a giant leech. with a violent effort, he tore his foot loose. he knew where he was now. death swamp and its quicksand.