What has constantly changing amount of salt in the water

During the winter, this species of fox has white fur, but in the summer, it has brown fur. what environmental change may have lead to this fox's fur color? snow cover increase in sun's brightness volcanic eruption global warming

If a cell is placed into a hypertonic environment,what will happen to it ? a)it will shrink or shrivel b)nothing c)it will burst d) it will expand or enlarge

There are two tomato plantlets one of them is kept in an oxygen chamber with a light source and another is kept in sunlight. both of them are watered regularly what will be the observation after two weeks