35. What does the writer mainly discuss in paragraph 1?
1. The Great Barrier Reef’s influences on the ecosystem
2. The Great Barrier Reef’s popularity among tourists
3. The Great Barrier Reef as the protector of marine life
4. The Great Barrier Reef’s duty of maintaining the complicated balance of marine lives
5. The Great Barrier Reef as one of the world’s natural wonders and the planet’s most fragile
ecosystems