<s>[INST] context: Autoimmune destruction of parietal cells would lead to decreased secretion of gastric acid and intrinsic factor. The diminished availability of intrinsic factor would result in poor absorption of dietary vitamin B12. Over time, the vitamin B12 deficiency could lead to pernicious anemia, which is characterized by increased production of macrocytes (megaloblasts) by the bone marrow. Because of the decrease in gastric acid secretion, luminal bacteria would most likely exhibit increased (not decreased) growth. One of the functions of HCl secreted by the parietal cells is to sterilize the gastric lumen. Patients with Type A gastritis have an increased likelihood of developing gastric carcinoma. A decrease in acid secretion leads to increased secretion of gastrin by antral G cells. This is because low gastric pH (less than 3) inhibits gastrin secretion paracrine release of somatostatin from cells in the gastric mucosa that can sense the acidity. With decreased parietal cells, the pH of the gastric lumen would rise and remove this inhibitory component. [/INST] question: Which of the following conditions would most likely be associated with chronic gastritis (Type A) resulting from autoimmune destruction of parietal cells? | options: A: Decreased growth of luminal bacteria B: Decreased likelihood of developing gastric carcinoma C: Decreased plasma concentration of gastrin D: Increased production of macrocytic red blood cells | answer: D </s>