The answer to this question is C. You can just read the sentence with the given choices and you will be able to figure out why C is the best answer. If you would use “although it appears,” this will not make any sense.
This can be used when making a compound system but for this one, it will not have the right subject and verb to make the sentence stand alone.
If you would use “it appears,” it will not be too clear what will appear and what will not in the final draft. “Despite its appearance” cannot be used too because there will not be any subject available. Only C will make sense when you use it.
What appears-after reading the sentence, we identify a main verb, a full predicate and a place phrase before the main verb. this leads us to anticipate some form of main subject.
it is not letter d because it has a verb of its own and the main sentence would still lack a main subject. it is not letter b because there is no connector to join both verbs. it is not letter a it does not have an appropriate connector to join both verbs; the sentence would still lack a main subject. the correct answer is letter c.