Çözüldü Energy Conversion

https://i72.servimg.com/u/f72/19/97/10/39/energy10.png

On this system where gravity is (g), only the horizontal part between the points K and M where |KL| = |LM| is not smooth and is of constant friction. An object that has a mass of (m) is thrown towards the inclined plane and goes to the point N, then returns and stops at the point L. What was the initial kinetic energy of the the object as m·g·h?

A) 2
B) 4
C) 6
D) 8
E) 10

Initial kinetic energy: E
Energy consumed on [KL]: e = 2(m·g·h)
E - 2e = 2(m·g·h)
E - 2[ 2(m·g·h) ] = 2(m·g·h)
E = 6(m·g·h).