The Largest Difference Between Mars' Northern and Southern Hemispheres Is

Multiple Choice

The largest difference between Mars' northern and southern hemispheres is that:

A) the southern appears older, with more impact craters.
B) the northern has all the outflows and must have been much hotter.
C) the northern is higher overall, despite some high volcanoes in the south.
D) the southern has a polar cap, but none ever forms in the north.
E) the southern is much darker, with large mare-like basaltic lava flows.