Which of these accidents plays a prominent role in Edith Wharton's novel "Ethan Frome"?

First published in 1911, "Ethan Frome" is a short novel by the American author Edith Wharton (1862-1937).

It is set in Starkfield, a fictional small town in Massachusetts. Using a technique popular at the time, it takes the form of a framework narration. The unnamed narrator encounters Ethan, who suffers from a severe limp. The townspeople are very cagey and unforthcoming about what caused this.

By chance, the narrator hires Ethan as a driver, and the latter spends a night at his home when a blizzard strikes. This is where the focus changes to Ethan's story. He was locked in a loveless marriage with the snobbish and sickly Zeena, and fell in love with her cousin Mattie, who helped out in their household. They suffer agonies repressing their feelings, but when they are finally able to spend an evening alone together, a seemingly trivial incident has far reaching consequences. Mattie takes down an expensive pickle dish, and the cat knocks it off the table. Zeena will late discover this and bitterly reproach Ethan.

On a winter's night, Ethan and Mattie take a moonlit sleigh ride down a local hill. The first ride is exhilarating, but then, seeing the hopelessness of their situation, they decide to take their own lives by crashing the sled into a wall. They survive, but both are horribly injured, Mattie being paralysed for life. This changes her sweet nature entirely, and Ethan, in a bleak ending, is left caring for two demanding and loveless women.