considering conservation of energy
total energy at releasing point at A = energy at C + fricitional energy loss in section CD + spring energy stored.
mgH = mgh + u mg h + 0.5* k x^2
2 mgh - mgh - 0.25 mgh = 0.5 k x^2
0.75 mgh = 0.5 k x^2
(3/4) mgh = (1/2) k x^2
x^2 = (3/2) mgh / k
x = sqrt ( 3 mgh / 2k)
option (f) is correct
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