Why The Smith chart is a graphical plot of the complex reflection coefficient, but it is overlaid with a grid of normalized impedance. Points of constant resistance form complete circles, and points of constant reactance form arcs that run off toward the edge, so any impedance R + jX plots where its resistance circle crosses its reactance arc. Values are normalized to the line impedance, so the center of the chart is 1.0 (a perfect match, typically 50 ohms).
Watch out The choices mentioning voltage and current are wrong because the chart's grid is impedance based, not a plot of instantaneous voltage or current; and nothing on a Smith chart is drawn as straight lines or chords, the curves are circles and arcs.
Smith chart = R circles + X arcs. Resistance makes full circles, reactance makes arcs curving to the rim.