What is one property that distinguishes thermoplastics from thermosetting plastics?

The distinguishing property of thermoplastics is that they can reshape upon heating. This means that when thermoplastics are heated, they become pliable and can be remolded into different shapes or reprocessed. Once cooled, they retain their new shape but can again be heated and reshaped multiple times without undergoing any significant chemical change. This characteristic makes thermoplastics very versatile for various applications, allowing them to be used in processes such as injection molding and 3D printing.

In contrast, thermosetting plastics, once cured or set into a fixed form through heat or chemical processes, cannot be reshaped or remolded. This key difference influences their respective usages in manufacturing and engineering applications. The other options do not accurately capture the fundamental difference between the two types of plastics. For example, while some thermoplastics can be rigid, not all are; likewise, thermoplastics are not inherently chemically unstable, nor do they all degrade in sunlight compared to certain thermosetting plastics that are known for their stability.