Deer mice normally do not travel far from their nests, and deer mice that are moved more than half a kilometer from their nests generally never find their way back. Yet in one case, when researchers camped near a deer mouse nest and observed a young deer mouse for several weeks before moving it to an area over two kilometers away, the deer mouse found its way back to its nest near their camp in less than two days.
Firstly, I'm happy that he reached back to his nest safely
Secondly, we have to find a cause which might have helped the mice to reach to his nest.
(A) The area to which the deer mouse was moved was dryer and more rocky than the area in which its nest was located.
Since we are not familiar with the overall terrain, this option becomes irrelevant for the argument.
(B) The researchers released the deer mouse in a flat area across which their campfire smoke drifted.
Smoke drifted on the flat area. Okay. So what if the mouse can smell the smoke or can trace the heat marks? He can follow the smoke to its source n hence can reach to his nest. So this option can help. Let's keep it.
(C) There were very few deer mice in the area to which the deer mouse was moved.
Irrelevant
(D) The researchers had moved the deer muse in a small dark box, keeping the mouse calm before it was released.
We don't the reason why mice couldn't find its way back to its nest. Was it because of panicking? We don't know. Hence this option is irrelevant.
(E) Animals that prey on deer mice were common in the area to which the deer mouse was moved.
Irrelevant.
Hence option B is the correct answer.