The correct answer is: A. pyramid.
A pyramid is more stable than a prism of the same height when they lie with their base on the surface. This is because the pyramid has a larger base area, which provides more support. The prism, on the other hand, has a smaller base area and is therefore more likely to tip over.
To understand this, imagine trying to balance a book on its edge. If you place the book on its narrow edge, it will be very unstable and will easily fall over. However, if you place the book on its wide edge, it will be much more stable and will be less likely to fall over.
The same principle applies to the pyramid and the prism. The pyramid has a larger base area than the prism, so it is more stable. The prism, on the other hand, has a smaller base area and is therefore less stable.
In addition, the pyramid has a wider base than the prism. This means that the pyramid has a larger moment of inertia, which makes it more resistant to tipping over. The prism, on the other hand, has a smaller moment of inertia and is therefore more likely to tip over.
Therefore, the pyramid is more stable than the prism of the same height when they lie with their base on the surface.