A Middle-Aged Man Accosts You in a Campus Building and Insists

A middle-aged man accosts you in a campus building and insists on telling you that several horses must have gotten into the building because he can hear them whinnying wherever he goes. You do not hear any sounds and cannot see any animals. This man is probably suffering from

A) abnormal excitement.
B) a hallucination.
C) a delusion.
D) disorientation.