Should time, or nature, or necessity, or chance, or the elements be considered as the cause, or he who is called the person (purusha, vignanatma)? It cannot be their union either, because that is not self-dependent, and the self also is powerless, because there is (independent of him) a cause of good and evil.

In plain words: The students wonder if the cause of everything is time, nature, fate, chance, the elements, or a conscious person. None of these alone, or even together, seems to stand on its own, and the individual self also seems powerless over good and bad things.