Ans . D
Gastrin is a polypeptide hormone produced by the enteroendocrine ceils of the stomach after exposure to mechanical stimuli or stimulation of vagus nerve and of the duodenum, after the exposure of chyme that contains undigested proteins. It plays an important role in the control of gastric acid secretion. Inhibin hormone Is secreted from corpus luteum, placenta and testes. It supplements the effect of excess sex hormones for depressing gonadotrophic activity (FSH, LH, ICSH). The target of inhibin is anterior lobe of pituitary. Duodenal enterokinase converts trypsinogen to activate trypsin which, in turn, activates the other pancreatic enzymes. Atrial natriuretic factor (ANF) is released by walls of the cardiac atrium in response to high sodium concentration, high extracellular fluid volume, or high blood volume. It then acts via various mechanisms to excrete Na, and to cause vasodilation in the circulatory system. It dilates the afferent glomerular arteriole, constricts the efferent glomerular arteriole, and relaxes the mesangial cells. The increases the glomerular filtration rate, resulting in greater excretion of Na+and water. It also decreases NaNa resorption in the renal distal convoluted tubule and cortical collecting duct. It also inhibits renin secretion.