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
A 30 year old unmarried woman of average socio-economic background believes that her boss is in secretly love with her. She rings him up at odd hours and writes love letter to him despite his serious warning not to do so. She holds this belief despite contradiction from family members & his denial. However she is able to manage her daily activities as before. She is most likely to be suffering from: 
Select and explain. 
A. Depression, B. Shizophrenia, C. Delusional disorder, D. No psychatric ailment
C: Delusional disorder
Answer: C: Delusional disorder 
Explanation: C. i.e. Delusional disorder The lady is suffering from Erotomanic delusional disorder in which the content of delusion is that another person usually of higher status, is in love with the individual. Apa from delusional area, the personality, behaviour & functioning is not markedly impairedQ (almost normal) - characteristic of delusional disorder.