A Patient with Bipolar Disorder Asks the Nurse, Why Did

A patient with bipolar disorder asks the nurse, Why did I get this illness? I don't want to be sick. The nurse would best respond with,

A) People who develop mental illnesses often had very traumatic childhood experiences.
B) There is some evidence that contracting a virus during childhood can lead to mental disorders.
C) Sometimes people with mental illness have an overactive immune system.
D) We don't fully understand the cause, but mental illnesses do seem to run in families.