This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
Antacid combinations of magnesium and aluminium salts are superior to single component preparations because. 
Select and explain. 
A. They have rapid as well as sustained acid neutralizing action, B. They are less likely to affect gastric emptying, C. They are less likely to alter bowel movement, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: (Ref: KDT 6/e p635) Mg (OH)2 has a quick onset whereas Al (OH)3 acts for a long time. Magnesium salts cause osmotic diarrhea whereas aluminium salts cause constipation. Combination of these two agents minimizes the impact on bowel movements.