Which detail contributes to the irony in “The Colomber” by Dino Buzzati?

a. “It’s the fish that sailors fear above all others.”
b. “When Stefano Roi was twelve years old”
c. "Despite my forty years, I believe I still have good eyesight.”
d. "as soon as he was a man, he found a dignified and well-paying position at an emporium."