The sentence in bold is a:
A supporting detail refers to an additional piece of information that is geared at adding meaning and understanding to the sentence. Without the supporting detail, the sentence will still be okay.
The idea of the supporting detail, in this case, is to explain why plastics can be referred to as having special properties. When writers use supporting details, their aim is to explain or give more weight to the main point that they stated initially.
Learn more about supporting details here:
https://brainly.com/question/540693
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