Are you here to post the answer? Because at the end of your question is the right answer. The answer you are looking for is a: "Story within a story."
Answer: It is ironic that as people have gained enough experience to be wise; they are returned to a state of infancy and enfeeblement.
Explanation:
I have completed the test and got a 100% (this question included)
No it is not. It is an adverb phrase since it lacks a subordinating conjunction.
Adverb clauses must be preceded or started by a subordinating conjunction such as after, if, because or although. For a sentence to qualify as an adverb clause it must include in its body a subject and a verb.
As a general rule you can use the following formula:
An adverb clause equals a subordinate conjunction plus a subject plus a verb, and it should be answering how? when? where? or why?
