Hey there!
"as if it had no weight" is an example of a dependent clause.
1. it can not be an independent clause becase it does not make sense by itself. Remember that independent clauses are the one that are able to transmit meaning without any help.
2. There is conjugation, then it's not a phrase. A phrase has neither subject nor verb, it can't form a 'predicate'; in this case, we have a suject "it" and a conjugated verb "had."
4. Parallel structure is the repetition of a chosen grammatical form within a sentence. Example: She likes hiking, attending the rodeo, and taking afternoon naps. As you can see, all the verbs come in the ING form. It does not apply in this example because we do not have that structure.
Finally, we have a dependent clause, which is the correct answer. It is a dependent clause since it is subordinate; it depends on the main clause (the independent one) to be semantically correct, to have a real meaning. The use of "as" marks an exemplification and we are missing the first clause.
Hope this helps.
