Which of the following is likely to cause ulcer in the stomach?

The correct answer is Option (2) → Aspirin

Aspirin (acetylsalicylic acid) is a non-narcotic analgesic. It relieves pain by inhibiting the synthesis of prostaglandins, the chemicals that cause inflammation and pain. Prostaglandins also protect the inner wall of the stomach, by keeping up its mucus layer and limiting acid secretion. When aspirin blocks them, and also acts directly as an acid on the stomach lining, the wall is irritated and can bleed. Regular use of aspirin can therefore lead to an ulcer in the stomach.