Answer:
Adverb clause: since advertisements are sometimes misleading,
Subordinating conjunction: since
Word(s) modified: read
Explanation:
An adverb clause is a group of words that have at least a subject and a verb, and whose function is to act as an adverb, that is to say, to modify or to add more detail to an adjective, a verb or another adverb. This type of clauses are dependent and they often answer questions such as "Why?", "How?", "When?", "Where?" and "In what circumstances?"
"Since advertisements are sometimes misleading" is an adverb clause because it modifies the verb "read" and it answers the question "Why should you read labels carefully?"
Subordinating conjunctions are conjunctions that introduce a subordinating (or dependent) clause, or that join dependent clauses to independent clauses. "Since" has that function in the sentence.
