A body of mass 5 kg makes an elastic collision with another body at rest and continues to move in the original direction after collision direction after collision with a velocity equal to $\large\frac{1}{10}$th of its original velocity. Then the mass of the second body is :

Question

$$\begin {array} {1 1} (1)\;4.09\;kg & \quad (2)\;0.5\;kg \\ (3)\;5\;kg & \quad (4)\;5.09\;kg \end {array}$$