Final answer:
The underlined portion of the sentence, "As sure as sparks fly upward," is considered a dependent or subordinate clause because it cannot stand alone as a complete sentence and provides additional context to the main clause.
Step-by-step explanation:
The underlined portion of the sentence, "As sure as sparks fly upward," is a type of clause. To determine the type of clause it is, we should look at its function in the sentence. A dependent clause is a group of words with a subject and a verb that cannot stand alone as a complete sentence because it does not express a complete thought. It needs an independent clause to give it meaning. Conversely, an independent clause can stand alone as a complete sentence.
In this case, the underlined portion "As sure as sparks fly upward" does not form a complete thought alone and requires the rest of the sentence for context. It begins with "as," which is a subordinating conjunction, marking it as a dependent clause. Therefore, the appropriate label for the underlined portion would be either a dependent clause or a subordinate clause since these terms are often used interchangeably.