If dark matter suddenly decays into photons or other energy forms, which of the following would begin to occur?

The choice that indicates galaxies in clusters would begin to fly apart is correct because the decaying dark matter would release energy in the form of photons or other energy particles. This sudden transformation would likely increase the kinetic energy of the system, providing the galaxies with an additional outward push. As a result, the gravitational binding forces, which keep galaxies clustered together, may be insufficient to counteract the increased outward momentum caused by the released energy from the decay of dark matter. Thus, we would observe an increase in the separation between galaxies, leading them to fly apart.

In the context of cosmic forces, dark matter plays a critical role in the structure formation of the universe by providing additional gravitational pull that holds galaxies and clusters together. A change in the nature or existence of dark matter, such as its decay into other forms of energy, would significantly disrupt this balance, allowing for the observed disconnection of galaxies.

Addressing other options briefly, merging of galaxies would not be a direct result of dark matter decaying; rather, we'd expect galaxies to become less bound to one another. The drastic contraction of the universe is unlikely since dark matter's gravitational influence would diminish, making collapse less probable. Lastly, the cosmic background radiation wouldn't just disappear, as it is a product