We had been silent a long time, and the edge of the sun sank nearer and nearer the prairie floor, when we saw a figure moving on the edge of the upland, a gun over his shoulder. He was walking slowly, dragging his feet along as if he had no purpose. We broke into a run to overtake him. How does the imagery in this passage from My Antonia help readers understand the theme “The prairie destroys those who are not prepared to live on it”?

The father’s walk happens at the end of the day.
The fast children overtake the weak and slow footsteps of the father.
The setting sun shows the quiet on the prairie.
The prairie floor makes the prairie seem like a house.