Costa Rica has one of the highest densities of species in the world, hosting approximately 5% of Earth's known species. This is a result of its unique geographic location, tropical climate, and diverse ecosystems. Therefore, the correct answer is A, species.
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Costa Rica boasts one of the highest densities of species in the world, hosting roughly 5% of the planet's known species within its diverse ecosystems. The country's unique geographic and climatic conditions support a wide range of flora and fauna, making it a key area for biodiversity. Its rich environment also promotes ecotourism due to the variety of habitats present. ;