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: Medicine
Treatment of choice for chronic ulcerative colitis is 
Select and explain. 
A. 5 aminosalicylic acid, B. Azathioprine, C. Metronidazole, D. Salicylates
A: 5 aminosalicylic acid
Answer: A: 5 aminosalicylic acid 
Explanation: In mild to moderate cases of ulcerative colitis, the combination of a once-daily oral and a topical 5-aminosalicylate preparation is effective. MOA of the drug is it modulate cytokine release from mucosa. Reference : Davidson, 23rd Edition, page no : 820.