Answer:
D. In equilibrium, there will be approximately 40 x particles in A and 40 x particles in B, and those numbers will fluctuate but will remain near 40.
Step-by-step explanation:
The perfect euilibrium is hard to achieve given the fact that particles move and are in constant change, but the equilibrium is reached when both boxes have a close number of particles in each of them, for example 41 and 39, 40 and 40, 42 and 38, this change in the number of particles is due to the movement of the particles, but it is still reachable.