Hi. In the given problem, there are two balls Mass of the first ball is M one is equal to two kg and mass of the second one is M two which is one below ground. The initially speed means speed before collision. Initially speed off the first wall Is M one i. is equal to 25 mita for second. And initially speed off the second ball is and that is we not. We won. I and we do. I. You just give an ass 20 meter for second. Now, after the collision speed of the second, ball speed of the first ball means we one F. That is equal to minus 2.5 m/s. Here, negative sign represents that the direction of motion of the first of all is reversed. Similarly, the direction of motion of the second ball is also reversed so its velocity not the speed, its velocity will be minus 35 meter per second. Now we will find the kinetic energies of the system comprising of the two balls before collision and after collisions. So first of all, total kinetic energy of the system before collision is E. G I. And that will be given us half into em burn into even I square glass, half Into empty into V two I square. So plugging in or non values E k I is equal to half into two kg into square of 25 m/s plus half into one program into 20 meter per second to the whole square. So here it comes out to be 625 glass, 200 Jews. Or we can say the kinetic energy of the system before collision is 825 jewels. Now in the similar method car net energy of the system after collision and that is E G A F. Which has given us half and one we even F square plus half M two V two F sq Plugging in non values. Again, this is half into two kg into for everyone. F this is minus 2.5 to the whole square plus half, into one kg Into -35 to the whole script. So here it comes out to be 6.25 plus six, 112.5 jules. When adding it, it comes out to be 618 .75 Jews means it is clear that the kinetic energy of the system is decreasing after the collision. It is less than that before the collision, so as kinetic energy of the system is decreasing, so it must be and in elastic collision. And moreover, as the balls are not sticking together of part a coalition, so it is not are perfectly last, perfectly inelastic collision hands here, our option is correct. According to which the coalition is simply In the last eight, not the perfectly in the last day. Thank you.