What aspect of human ability is discussed here in Chapter Twenty-five?

I'm not sure what you mean by ability, but the migrants and the small farmers in this chapter definitely show the landowners and the world their perseverance. Regardless of what's happening around them.... they do the best they can to bring in their crops before they're ruined. There is anger and resentment everywhere, but people keep doing what they can.....

“In the souls of the people, the grapes of wrath are filling and growing heavy, growing heavy for the vintage.”