Concept:The learning curve shows progress over time. A plateau is a flat region where no improvement is observed, often due to physical or mental tiredness.Explanation:Learning typically moves through three stages: a slow beginning, a period of steep progress, and finally a plateau. The plateau occurs after the learner has mastered the skill and begins to feel bored or fatigued from repetitive practice. Fatigue reduces motivation and concentration, halting further improvement. Among the given options, fatigue is the direct cause of a plateau; maturation, motivation, and interest would normally aid learning rather than cause a halt.
