The approximate height from the surface of earth at which the weight of the body becomes \( \frac{1}{3} \) of its weight on the surface of earth is: [Radius of earth \( R = 6400 \, \text{km} \) and \( \sqrt{3} = 1.732 \)]
\( 3840 \, \text{km} \)
\( 4685 \, \text{km} \)
\( 2133 \, \text{km} \)
\( 4267 \, \text{km} \)