Final answer:
The cosmic microwave background radiation (CMB) would not disappear if dark matter were removed from the universe. The CMB exists independently of dark matter, as it is radiation from the time the universe became transparent and it reflects density fluctuations of ordinary matter, not dark matter. Thus, option C is the correct answer; other structures held together by dark matter's gravity, such as galaxies and clusters, would indeed be affected.
Step-by-step explanation:
If all the dark matter in the Universe were to be instantaneously removed, galaxies and clusters of galaxies would suffer severe disruption, as they contain about 10 times more dark matter than luminous matter. This dark matter provides the necessary gravitational force that keeps galaxies and clusters bound together. Hence, if dark matter were removed, galaxies would fly apart and clusters would disintegrate because there would not be sufficient gravity to hold them together.
On the other hand, the cosmic microwave background radiation (CMB) would not disappear if dark matter were removed. The CMB is a relic from the early universe, a snapshot of the radiation at the moment the cosmos became transparent, about 380,000 years after the Big Bang. It provides us with information about the density fluctuations in the early universe for ordinary matter that interacts with radiation. As dark matter does not interact with photons, its removal would not cause the CMB to vanish, therefore option C) is the correct answer.
Finally, gravitational lensing, which is a phenomenon that occurs when a massive object like a galaxy cluster bends the light from objects behind it, would significantly decrease because the mass, hence the gravitational force, of the clusters would be reduced without dark matter.