The right answer to this question is option A. Water moves in to dilute the sugar in the bear, causing it to swell.
That happens because there is a process involving water called osmosis. This process is pretty simple to understand. What happens is that the water will move from a place to another because of the concentration of solute. So, in this case, we have a higher concentration of solute inside the bear, and a lower one in the water, and for that, things need to be equal to reach the right balance between both concentrations. Once that happens, that water swells the gummy bear to balance these two them, and that's called osmosis.
