The husband of a woman with a somatic symptom illness asks the nurse why the doctors cannot find anything wrong with her. What is the appropriate explanation for the nurse to offer?

"She controls the symptoms when she isn't feeling much stress. It is hard to diagnose when the symptoms are intermittent."

"There is a physical cause. It just has not been detected yet."

"She is not really experiencing the symptoms. She is making them up to get attention."

"There is no physical cause. Mental distress is causing the symptoms, even though she is not aware of it."