✅ Option C, "atop a rugged cliff," correctly identifies the entire prepositional phrase. It begins with the preposition "atop" and includes its object "cliff," along with the adjective "rugged" modifying the object.

❌ Option A, "majestically atop," incorrectly includes an adverb ("majestically") that modifies the verb "stood," and only the preposition, not its object.

❌ Option B, "a rugged cliff," is only the object of the preposition, missing the preposition itself.

❌ Option D, "overlooking the stormy sea," is a participial phrase, not a prepositional phrase, as "overlooking" is a present participle functioning as an adjective modifying "cliff."