1. According to kinetic theory of ideal gases, molecules of a gas are in incessant random motion, colliding against each other and with the walls of the container. All these collisions are perfectly elastic collision.

2. In perfectly elastic collision, total kinetic energy of gas is conserved.

3. Here, we have a mixture of oxygen and hydrogen gas. Therefore

K.E of oxygen + K.E of hydrogen=constant

4. So, if kinetic energy of oxygen molecules increases, then kinetic energy of hydrogen molecules decreases or vice-versa so that, sum of both kinetic energies remains constant.

5. Therefore, both option (c) and (d) are correct.