In the winter its color changes to more resemble their <em>winter</em> surroundings, so they are more white, enabling them to blend in better with their white surroundings. In summer, its color changes to more resemble its <u><em /></u><em>summer</em> surroundings, so they are more brown like the rocks and ground around them.
The correct option is C.
Science is a dynamic subject and it changes all the time. In the science field, research is always on going and when new evidence are discovered about a particular topic, the new evidence are usually used to update the scientific information that is already on ground. All the areas of science listed about have enjoyed scientific updates in the recent past.