Why is Ann afraid when she sees smoke in z for Zachariah?

In "Z for Zachariah," Ann is afraid when she sees smoke because it signals the presence of another person in a post-apocalyptic world where she believed she was alone. The smoke represents both a potential threat to her safety and the uncertainty of what this new presence might bring. Ann's fear stems from her isolation and the dangers that could arise from encountering another Survivor, especially in a world where trust is fragile. This moment heightens the tension and anxiety surrounding her survival.