A thin 16-year-old girl is brought in the ED after collapsing at home. Her initial vitals include an HR of 110 beats per minute, BP of 80/55 mm Hg, and an RR of 18 breaths per minute with an oxygen saturation of 98% on room air. Upon physical examination, you note a cachectic female in mild distress. Her chest is clear to auscultation; her sunken-in abdomen is soft and nontender. Upon inspecting her extremities, you notice small areas of erythema over the dorsum of her right hand distally. Given this patient’s presentation and physical examination, which of the following etiologies must be further explored in this patient?

a. Bulimia b. Gastroenteritis c. Malingering d. Factitious disorder e. Suicidality