This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Disruption or disorganization of biological rhythm is observed in - 
Select and explain. 
A. Schizophrenia, B. Anxiety, C. Depression, D. Mania
C: Depression
Answer: C: Depression 
Explanation: Diurnal variations symptom severity and alterations in circadian rhythmicity of number of neurochemical and neurohumoral factors suggest that biologic differences may be secondary to a primary defect in regulation of biologic rhythms.