The abbreviation for liter is?

The abbreviation for liter is represented as "L". This is a standardized symbol recognized internationally for measuring volume in the metric system. The choice "L" is clear and universally accepted in scientific and medical contexts, making it the correct answer for denoting liters.

The other options represent different units of measurement: "kg" stands for kilogram, which is a unit of mass; "g" represents gram, another unit of mass; and "mg" stands for milligram, which is a smaller unit of mass. None of these abbreviations relate to volume, which is why they are not suitable choices for this question. Therefore, understanding that "L" is specifically designated for liters underscores its importance in medication math and dosage calculations where volume is often crucial.