Correct Option
The correct option is (a).
Explanation
Biodiversity, or biological diversity, refers to the variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part. It is generally understood at three levels: genetic diversity, species diversity, and ecosystem diversity.
Statement-wise Analysis
- Statement 1 is Correct: Biodiversity fundamentally refers to the variety of life forms existing on Earth, encompassing microorganisms, plants, and animals.
- Statement 2 is Incorrect: Biodiversity is not merely a collection of species; it includes the ecological complexes and systems they form. Consequently, it encompasses the interrelationships and interactions among organisms (such as food webs and symbiosis).
- Statement 3 is Incorrect: The definition of biodiversity extends to ecosystem diversity, which explicitly involves the interaction of biotic communities with their abiotic environment (soil, climate, water). Therefore, relationships with the environment are an integral component of biodiversity.
Key Takeaway: Biodiversity is a holistic concept that includes not just the count of species, but also the genetic variability within them and the ecological interactions they have with each other and the environment.