Which type of chromatography uses a gas carrier?

Gas chromatography (GC) is defined by the use of a gas as the carrier phase for transporting the sample through the column. In this technique, the sample is vaporized and then carried by an inert gas, such as helium or nitrogen, which helps in the separation of the different components of the mixture based on their volatility and interaction with the stationary phase inside the column.

In contrast, liquid chromatography uses a liquid as the mobile phase, and solid phase chromatography typically involves a solid stationary phase with a liquid carrier. Service chromatography isn't a recognized type of chromatography, which makes it irrelevant to the question. Therefore, the unique characteristic of gas chromatography—utilizing a gas carrier—clearly distinguishes it as the correct answer.