This answer is the one that most lends support to the dark energy theory. We know that the idea of an energy that exerts pressure on the universe was proposed by Einstein in 1917. If Einstein is wrong about the existence of this pressure, then that would undermine the idea of dark energy, which is a kind of energy alleged to exert pressure on the universe. But if Einstein is right about the existence of this pressure, then that helps the dark energy theory by at least establishing the baseline assumption that there is some kind of pressure exerted on the universe. (A) provides evidence tending to support the idea that there is a source of pressure on the universe. If we need something like the cosmological constant to make sense of many other phenomena, that suggests the kind of pressure described by Einstein's cosmological constant exists.

This provides evidence against the idea that vacuum energy constitutes the dark energy that applies pressure to the universe. So it doesn't support the dark energy explanation of the universe's expansion.

It's not clear that virtual particles need to interact with nonvirtual particles in order for the virtual-particle-based version of dark energy theory to work. In any case, if (C) does anything, it might suggest that virtual particles aren't the origin of dark energy.

It's not clear how the relationship between distance and velocity of movements relates to the dark energy theory. The explanation that involves gravity is the second theory described in the last paragraph, not dark energy theory.

It's not clear how the theory of relativity relates to the dark energy theory. The explanation that involves the theory of relativity is the second theory described in the last paragraph, not dark energy theory. (Note that the cosmological constant mentioned in connection with the dark energy theory is different from the theory of relativity mentioned in the last paragraph.)