Correct Answer: (a) The discovery of the Sapphire-winged Warbler has sparked global interest in birdwatching.
Solution:The discovery of the Sapphire-winged Warbler has sparked global interest in birdwatching. The passage suggests that people worldwide, including ornithologists and bird enthusiasts, are excited about the discovery of the Sapphire-winged Warbler. They are traveling to the remote tropical island to see this unique bird. This indicates a global interest in birdwatching.