The answer that best matches the word in italics in the first sentence is D, "large and dark space". "Cavernous" is suggestive of a cavern in vastness, darkness.
As regards the second sentence, the word that best matches the word in italics is C, "a statement that contradicts itself". Cambridge dictionary defines "paradox" as a situation or statement that seems impossible or difficult to understand because it contains two opposite facts or characteristics.
In the third sentence, D is the correct answer. "Synchronization" in that case refers to the water ballet in which the movements of the dancers should go at the same time.
