There are some criteria which an ideal antacid should fulfill. Some of the criteria are given below: [P] The antacid should be absorbable orally and should buffer in the pH range of 4 - 6 [Q] The antacid should exert its effect rapidly and should not cause a large evolution of gas [R] The antacid should not be a laxative or should not cause constipation [S] The antacid should react with the gastric acid and should inhibit pepsin Choose the correct combination of criteria for an ideal antacid.