How does the sun help deers?

All living creatures need sunlight to survive. Deer capture necessary vitamins from the air. Not to mention it helps them see. Plants, such as grass, also require sunlight. The deer eat the plants and absorb the energy from the sunlight the plant also absorb. So in short, deer and any living creature get their energy all from the sun as it is transferred to one creature to the next. Hope this helped!! :)