Which of the following IV solutions contains potassium?

The correct choice indicates that the solution contains potassium because it explicitly mentions the addition of 20 mEq of potassium (K+). This means that the IV solution is designed to provide potassium to the patient, which is essential for various physiological functions, including muscle contractions, nerve signaling, and maintaining fluid balance.

To further clarify the context of the other choices: Normal Saline (0.9% NS) is a widely used IV solution that primarily consists of sodium and chloride, but it contains no potassium. The combination of Normal Saline with Dextrose also does not include potassium unless specified otherwise. Although an Electrolyte Maintenance Solution may contain potassium and other electrolytes, it does not ensure the presence of potassium without specific formulation details. The mention of "20 mEq K+" in the correct choice is a clear identification of potassium content, distinguishing it from the other options.