This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pelvis and Perineum 3, Subject name: Anatomy
TRUE about anal membrane: 
Select and explain. 
A. Perforates at 6 weeks, B. Develops from anterior pa of cloacal membrane, C. Lies at proximal pa of proctodaeum, D. Covers urogenital sinus
C: Lies at proximal pa of proctodaeum
Answer: C: Lies at proximal pa of proctodaeum 
Explanation: Anal membrane develops from posterior (not anterior) pa of cloacal membrane, lies at proximal pa of proctodaeum and covers primitive rectum (not urogenital sinus). During development, cloaca ( at distal end of hindgut ) is covered by cloacal membrane which has two pas. Urogenital membrane is the ventral (anterior) pa to cover primitive urogenital sinus. Anal membrane is the dorsal (posterior) pa to cover primitive rectum. Anal membrane perforates at 9th week to let open the gut tube to the exterior at proctodaeum.