Read the following passage from "First Confession" in which the main character has just entered the confessional.

It must have been then that I noticed the shelf at about one height with my head. It was really a place for grown-up people to rest their elbows, but in my distracted state I thought it was probably the place you were supposed to kneel. Of course, it was on the high side and not very deep, but I was always good at climbing and managed to get up all right. Staying up was the trouble...

"What are you doing up there?" he shouted in an angry voice, and the strain the politeness was putting on my hold of the molding, and the shock of being addressed in such an uncivil tone, were too much for me. I lost my grip, tumbled, hit the door an unmerciful allop before I found myself flat on my back in the middle of the aisle. The people who had been waiting stood with their mouths open. The priest opened the door of the middle box and came out, pushing his biretta back from his forehead; he looked something terrible.

Which of the following stylistic elements is used by the writer to create humor in these lines?
A. hyperbole
B. incongruity
C. irony
D. sarcasm

To determine which stylistic element is used by the writer to create humor in these lines, let's go through each option:

A. Hyperbole: Hyperbole refers to exaggerated statements or claims not meant to be taken literally. While there is an element of exaggeration in the passage (such as the protagonist climbing up the shelf), it is not the main element used to create humor.

B. Incongruity: Incongruity refers to the use of unexpected or contrasting elements that are incongruous with each other. In this passage, the use of the shelf as a makeshift kneeling place for confession is incongruous and unexpected, which adds a comedic effect.

C. Irony: Irony refers to a situation in which there is a contrast between what is expected and what actually happens. While there is a level of irony in the passage (such as the protagonist mistakenly thinking that the shelf is for kneeling), it is not the main element used to create humor.

D. Sarcasm: Sarcasm is the use of irony to mock or convey contempt. While there is some frustration expressed by the priest in his angry tone, it is not presented in a mocking or contemptuous way.

Based on the analysis, the correct answer is B. Incongruity. The unexpected use of the shelf as a kneeling place creates humor in the passage.