Here's why:

* Shape: Clingfilm holds its own shape unless stretched or deformed. This is a characteristic of solids.

* Volume: Clingfilm has a definite volume that doesn't easily change. Liquids, on the other hand, take the shape of their container.

* Structure: Clingfilm is made of long, chain-like molecules that are tightly packed together, giving it its rigidity. This structured arrangement is a hallmark of solids.

While clingfilm can be stretched and seems somewhat flexible, it retains its structural integrity. This indicates that it's a solid material.