The correct answer is option 2: Mild base.

Milk of Magnesia is a commonly used antacid and laxative that is used to relieve symptoms of indigestion, heartburn, and constipation. It contains the active ingredient magnesium hydroxide, which is a mild base.

When consumed, milk of magnesia works by neutralizing excess stomach acid, which can be a cause of indigestion and heartburn. The base reacts with the acid to form water and a salt, thereby reducing the acidity in the stomach. This helps to alleviate the discomfort and burning sensation associated with indigestion.

Additionally, milk of magnesia can also act as a laxative by increasing the water content in the intestines, which helps to soften the stool and promote bowel movements. This makes it a useful option for relieving constipation.

Overall, milk of magnesia is an effective and relatively mild option for managing indigestion and associated symptoms, due to its alkaline properties.