Answer:
Words that are sometimes prepositions can act as adverbs. A preposition requires an object. An adverb does not. A single word acting as an adverb answers where, when, how or to what degree about the verb.
Explanation:
After reading excerpt represented above I can clearly see the right answer from the scale attached above. Definitely, this paragraph uses standart compare-contrast organization, so now it is clear that the only correct option is the first one A. Comparison and contrast; cause and effect. Especially such words<span> as "however" and "on the other hand" are the prompts for you to understand why I think so.</span>
