Northturn Switzerland has a fairly cold climate caused by sea winds Atlantic ocean but southern Switzerland tends to be much warmer and sunnier. What could cause this difference?

A- Cool winds cannot blow across a large lake into the south.
B- Mountains prevent cold air from blowing over into the south
C- The south is at a much higher elevation, so it’s is closer to the sun.
D- Switzerland has experienced a drastic climate change in the past few years.