Which event foreshadows the resolution of The Cask of Amontillado?

The event that foreshadows the resolution in "The Cask of Amontillado" is when Montresor reveals his plan to seek revenge on Fortunato during the carnival season, showing his intent to carry out his sinister plot. This sets the tone for the dark and ominous atmosphere that ultimately leads to the resolution of the story – Fortunato's entrapment and demise.