Ans. is 'a' i.e., Ulcerative colitis Inflammatory bowel disease (crohn's disease & ulcerative colitis)o 5-aminosalicylic acid (5-ASA) is the main anti-inflammatory compound that acts locally in colon. It is the first line of treatment in mild to moderate UC and CD. When given alone 5-ASA is absorbed > 80% in proximal intestine and very little reaches upto colon. To decrease the absorption it may be associated with some innert compound.o Sulfasalazine (5-AS A + sulfapyridine), olsalazine (ASA+ASA) and balsalazide (5-AS A + aminobenzoylalanine) are effective in ulcerative colitis.o Different formulations of 5-ASA have been developed to deliver it to colon, called mesalamine.o Other drugs used in IBD are :-1. Glucocorticoids - They are used only for remission of U.C. and have no role in maintenance therapy.2. Purine analogues (Azathioprine, 6-MP) - Can be used for the induction and maintenance of remission of U.C. and C.D.3. Methotrexate - Can be used in CD, but has no use in U.C.4. Anti TNF-a (Infliximab, adalimumab, certolizumab, etanercept) - Can be used in CD.5. Cyclosporine - Used in severe U.C., which is refractory to glucocorticoids.6. Anti-Integrin therapy (Natalizumab) is recently approved for moderate to severe Crohn's disease not responding to other therapies. It is targeted against a4 subunit of integrins. The patient on natalizumab therapy should not be given other immunosuppressants due to risk of progressive multifocal leukoencephalopathy.