What is a defining feature of the pile of a carpet?

The defining feature of the pile of a carpet is that it provides a soft surface for comfort. The pile refers to the yarns that are raised on the surface of the carpet, which creates a plush, cushioning effect underfoot. This softness is not only important for the tactile experience but also contributes to the overall aesthetic and warmth of a space. Pile can vary in height and density, influencing the level of comfort and appearance, making it a crucial element in carpet design and functionality.

In contrast, the other options do not accurately reflect the essence of carpet pile. For example, a lack of textures (the first option) contradicts the very nature of pile, which is designed to have varying textures and depths. While some carpets can be firm and sturdy (the second option), this does not encapsulate the primary defining feature of pile itself, which is its soft and inviting nature. Lastly, the notion that pile cannot be secured (the fourth option) misrepresents how pile is constructed and attached during the manufacturing process, thereby failing to recognize its designed stability and functionality.