Question

Classify the underlined part of the following sentence by the type of phrase or clause it is. Obsidian is a black volcanic glass used today to make the sharpest surgical blades. A. adverb clause B. adjective clause C. adverb phrase D.adjective phrase

Answer 1

If the underlined part of the sentence us used today, then the correct answer is D. adjective phrase.
It isn't a clause because there is no verb here, so it is an adjective phrase.