Chromatography is an analytical technique used for the separation of mixtures. The mixture is dissolved in a fluid, which travels all the way through the structure holding the chromatography technique. This fluid which travels along the structure is known as the:

The correct options are
C moving phase
D mobile phase
The mixture/sample whose different components are to be separated using a chromatography technique is dissolved in a fluid. This fluid travels/moves all the way through the structure holding the chromatography technique. This fluid is known as the moving phase or mobile phase, since it travels all the way up or down the structure.