Respuesta :
A is wrong because galaxies do not move closer during expansion. C is wrong because it does not describe what gravity does on the distribution of matter. D is wrong because of similar reasons. So the only true answer to this question is B density of particles in space decreases when the universe expands.
Answer:
B. density of particles in space decreases when the universe expands
Explanation:
i just fished my exam and i got it right i even got it on my notes from my dba.
Also the particles (atoms) in the balloon(planet) cant make more witch means that the density of particles in space decreases when the universe expands and that's the Big Bang Theory