Answer:
B
Explanation:
In this sentence the adverb clause is: Although Denmark is located on a peninsula.
The subject of the sentences is <em>country.</em>
The verb is <em>includes. </em>
The adverb is <em>also. </em>
<em>More than 400 islands </em>is a prepositional phrase.
Adverb clauses can modify verbs, but they can also modify adverbs and adjectives, so it is always a good idea to identify the parts of speech of the sentence before deciding which one is modified by the adverb clause.