Here's why:

* Shape: Bread holds a definite shape, unlike a liquid which takes the shape of its container.

* Volume: Bread has a fixed volume, unlike a gas which expands to fill its container.

* Compressibility: Bread is not easily compressible, unlike a gas which can be compressed significantly.

While bread can be soft and may seem like it could be a liquid, its structure and properties clearly classify it as a solid.