Answer:
D. to introduce the topic
A failing grade on the assignment
<span>He takes his responsibilities seriously because he learns from his mistakes</span>
An adjective is <span>a word that names an attribute related to a noun to modify or describe it, thus the adjective in this sentence is "bravely."
Hope this helps.</span>
If you mean an adverb clause, I'd say your answer is D. Adverb clauses typically begin with a subordinating conjunction like because, after, if, or although.