An agent used to combat metabolic acidosis is?

Sodium bicarbonate is utilized to counteract metabolic acidosis because it acts as an alkaline substance that can neutralize excess acid in the body. In metabolic acidosis, the blood's pH level drops due to an increase in acidity, often caused by factors such as kidney dysfunction or the accumulation of metabolic waste. By administering sodium bicarbonate, the bicarbonate ions provide a buffering capacity to the blood, helping to restore a more neutral pH level and alleviate the effects of acidosis.

The other agents listed are not primarily used for this purpose. Magnesium sulfate is primarily indicated for treating conditions like eclampsia or severe asthma due to its muscle relaxant properties. Potassium chloride is mainly administered to correct or prevent low levels of potassium in the blood, not to correct pH levels. Albumin is a protein used for volume expansion and maintaining oncotic pressure in the blood but does not influence acid-base balance directly. Sodium bicarbonate remains the preferred choice for managing metabolic acidosis effectively.