Why did Kamal slip down in his performance?

Correct option is D

Explanation:\

Boredom or lack of engagement is a primary cause of declining academic performance—when methods fail to interest, students disengage.

Information Booster:

Interest and relevance in teaching are shown in educational research to be critical motivators for learner persistence and performance.

Additional Knowledge:

(1-3): These are contributing factors, but the uninteresting teaching method is the immediate reason for the decline.