A 20-year-old student fails an important exam and develops sadness, poor concentration, and irritability for 3 weeks. Symptoms resolve when he passes the next exam. Most likely diagnosis is:

Correct option is B

Adjustment disorder occurs when emotional/behavioral symptoms develop in response to identifiable stressor, lasting <6 months after the stress ends.
Explanation of options: (a) ✘ Major depression lasts ≥2 weeks but not strictly tied to external stress. (b) ✔ Correct; adjustment disorder = stress-linked transient symptoms. (c) ✘ Cyclothymia = mood fluctuations, not stress-specific. (d) ✘ Dysthymia = chronic low mood ≥2 years, not episodic stress-related.