19.
Your Answer is
Correct Answer is B
Explanation
Here is a parallel structure of three nouns: N1, N2 and N3, so the underlined part is modified by the noun magnificence and the adjective cool, and B is correct.
Item A: coolly is an adverb and cannot modify nouns, wrong.
Item C: cool is an adjective, and the noun form is used here, which is wrong.
Item D: Magnificent is an adjective, wrong.