A 26-year-old woman with a history of bitemporal hemianopsia and diabetes insipidus develops meningococcal infection and dies of septic shock. Examination of the brain at autopsy reveals a large...

A 26-year-old woman with a history of bitemporal hemianopsia and diabetes insipidus develops meningococcal infection and dies of septic shock. Examination of the brain at autopsy reveals a large cystic tumor mass replacing the midline structures in the region of the hypothalamus (shown in the image). This tumor is derived from epithelial cells originating in which of the following embryonic structures?

(A) Diencephalon

(B) Mesencephalon

(C) Nasopharynx

(D) Prosencephalon

(E) Third pharyngeal arch