What landform is identified on this map

Ascientist is explaining how background cosmic radiation gives evidence of the big bang theory. she says that radiation has been detected everywhere equally as heat in the universe and is increasing. this has been shown to be residual radiation from the big bang. what error did the scientist make?

Hurry on the map above, arrow 1 points to a region where most people are

Find the slope of the line (6,4) and (3,2)