Answer with Explanation:
One hypothesis above would probably rely on the situation called <em>"inelastic collision." </em>The two carts are travelling towards each other at different speed. So, this means that once they collide, the kinetic energy will not be conserved but will be transferred as <em>sound energy, thermal energy or material deformation</em>. The impact will be great, thus a <u>greater fraction of kinetic energy will be lost from the system.</u>
I think it is D because u think of space and Electromagnetic Waves Travel Through Space Moving All Kinds of Particles From The Sun With It Which Creates The Northern and Southern Lights In The Poles :-)