Final answer:
The best description of the author’s purpose in the passage is to explain Trinidad’s beauty and to entertain with a story, as it vividly sets up a scene for a narrative without persuading the reader, discussing the value of sailing, or focusing on the island's desolation.
Step-by-step explanation:
The author's purpose in the passage from Blackbeard, or, The Pirate of Roanoke a Tale of the Atlantic is C) to explain the beauty of Trinidad and to entertain with a story. The passage vividly describes the island's topography, its lush vegetation, and the sense of respite it provides to mariners, setting up a scene for a narrative that follows the landing of a boat. There is no explicit persuasion for the reader to visit Trinidad, nor information about sailing as a pursuit, nor a focus on how deserted the island is, which rules out options A, B, and D.