Correct option is D
The correct substitution of the highlighted segment is “sarcasm.”
Error identification: The sentence contrasts two approaches teachers use, so "sarcasm" is more appropriate as it aligns with the irony mentioned.
Grammatical Rule used: "Sarcasm" is a form of verbal irony intended to mock or convey contempt, fitting the context of the sentence.
Corrected sentence: Some teachers often praise their pupils' efforts while some use sarcasm and irony.