Meridians are vertical lines running from the North Pole to the South Pole and are used to measure longitude.
A. Contours – Incorrect. These lines show elevation and terrain on a map.
B. Isobars – Incorrect. These connect places with equal atmospheric pressure.
C. Meridians – Correct. These are lines of longitude from pole to pole.
D. Steppes – Incorrect. Refers to grasslands, not map lines.