Positive feed back is seen in A/E :: (A) LH Surge, (B) Entry of Ca into sarcoplasmic reticulum, (C) Stimulation of gastric secretion of histamine & gastrin, (D) Thrombolytic activity in coagulation cascade
Answer is C. C i.e. Stimulation of gastric secretion by histamine & gastrinMost control system of the body are negative feed back system. Release of acid in stomach by the action of gastrin is negative feed back system, as Tin acid secretion inhibits fuher gastrin secretion.