10 points! Where is the outer edge of the atmosphere

is it
a) 10 km above earth surface
b) 100 km above earth surface
c) 1000 km above earth surface
d) 10.000km above earth surface
e) 100.000 km above earth surface
f) 1.000.000km above earth surface

In diving we teach based on about 62.5 miles, so I'd say 100 km.

http://en.wikipedia.org/wiki/K%C3%A1rm%C…

b) 100 km above earth surface. ?