The diagnosis of celiac disease (gluten sensitive enteropathy) rests on proving that the problem arises from a reaction to gluten (a component of many grains). While the answer in A is correct in the sense that these are the diagnostic histological features of celiac, the findings are not specific for this disease and can be seen in many disorders including infection. To confirm a diagnosis of celiac, the person with these findings on biopsy must be put on a diet free of gluten to see if he or she responds (usually the response is monitored clinically, but sometimes they will rebiopsy to see if there is a histologic response to the treatment). Tests for HLA-DQ2 and DQ8, although not diagnostic, are helful in the diagnosis. If the patient does not have one of these two HLA genes, it is highly unlikely that they will have celiac disease. This can be helpful in difficult cases. The distinction of celiac from other forms of disease is important because the only cure is to go on a gluten free diet, which is difficult and expensive for the patient.