This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
Which of the following is not a permanent mucosal fold? 
Select and explain. 
A. Spiral valve of heister, B. Gastric rugae, C. Plica semilunaris, D. Transverse rectal fold
B: Gastric rugae
Answer: B: Gastric rugae 
Explanation: The gastric folds (or gastric rugae) may be seen during esophagogastroduodenoscopy or in radiological studies. They provide the stomach with increased surface area for nutrient absorption . image ref - britannica.com