Consider the following statements:1.Most of the world's coral reefs are in tropical waters.2.More than one-third of the world's coral reefs are located in the territories of Australia, Indonesia and Philippines.3.Coral reefs host far more number of animal phyla than those hosted by tropical rainforests.Which of the statements given above is/are correct?

1. A

   1 and 2 only

   (a) 1 and 2 only. Tropical concentration and the Australia–Indonesia–Philippines share are true, but statement 3 is also true: coral reefs host more animal phyla than tropical rainforests. Dropping 3 is incomplete. This option is not the key.

2. B

   3 only

   (b) 3 only. The phylum-richness claim is correct, yet statements 1 and 2 are also correct. This option is not the key.

3. C

   1 and 3 only

   (c) 1 and 3 only. Both hold, but more than one-third of reefs lying in Australian, Indonesian and Philippine waters is also accepted in this question. This option is not the key.

4. D

   1, 2 and 3

   (d) 1, 2 and 3. Most reefs are tropical; a large share sits in the Coral Triangle plus the Great Barrier Reef (Australia, Indonesia, Philippines); reefs shelter a higher count of animal phyla than rainforests. All three statements are correct. This option is the official key.

Summary. Official key is (d) 1, 2 and 3. Coral reefs cluster in warm shallow seas. Australia, Indonesia and the Philippines together hold more than a third of the global reef area. Despite a smaller carbon-biomass than rainforests, reefs support a greater number of animal phyla. None of the three statements is discarded. The stored key is therefore (d).