This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Physiology
Most impoant site for gastrin-producing cells 
Select and explain. 
A. Cardia, B. Fundus, C. Antrum, D. Duodenum
C: Antrum
Answer: C: Antrum 
Explanation: Gastrin is produced by cells called G cells in the antral poion of the gastric mucosa. G cells are flask-shaped, with a broad base containing many gastrin granules and a narrow apex that reaches the mucosal surface. Microvilli project from the apical end into the lumen. Receptors mediating gastrin responses to changes in gastric contents are present on the microvilli. Other cells in the gastrointestinal tract that secrete hormones have a similar morphology.Ref: Ganong&;s review of medical physiology 23rd edition Page no; 443