C. a strong enemy sitting on a horse and outlined by the sky.
Explanation:
This is the image that the description creates. In these lines, we learn that a soldier is looking up towards a figure. This is the figure of an enemy sitting on a horse. He is outlined by the sky, and from the soldier's perspective, he looks heroic and colossal in size. This is a vivid image that allows the reader to understand the point of view of the soldier.
