Final answer:
Utgard-Loki reveals that the competitions in the Prose Edda were rigged by magic to be impossible for Thor and his companions to win.
Step-by-step explanation:
In the Prose Edda, Utgard-Loki reveals to Thor and his companions that the competitions they participated in were deceptive and that he used magic to ensure their challenges were impossible to complete. For example, when Thor attempted to drink from a horn, it was connected to the sea, and lifting the cat was actually lifting the Midgard Serpent, which encircles the Earth. These revelations showed the gods' trials were meant to be unwinnable as a way to protect the kingdom from their strength.