Answer:
It introduces dangers that are not visible.
Step-by-step explanation:
this setting detail advance the plot by introducing danger that are not visible that is the dog did not want to go. It hung back until the man shoved it forward, and then it went quickly across the white, unbroken surface. Suddenly it broke through, floundered to one side, and got away to firmer footing. It had wet its forefeet and legs, and almost immediately the water that clung to it turned to ice.