The correct answer is B. Superficial
The sentence allows the reader to be induced that the missing word refers to the level of damage to the building, specifically the word only, which refers to something limited. According to the above, the word that best completes the sentence according to its context would be superficial because it groups the set of surface factors of the building such as its paint, its coating and what is in sight, without suffering structural damage. So, the correct answer is B. Superficial.