The correct answer is option 3, which is "Two lives." This refers to the fact that amphibians have a unique life cycle that involves living both in water and on land. They start their lives in water as aquatic tadpoles, breathing through gills, and then undergo a metamorphosis where they develop lungs and transition into their adult form. As adults, amphibians can live both in water and on land, taking advantage of both habitats. This ability to thrive in two different environments is a defining characteristic of amphibians. It allows them to access different food sources, breed in water, and escape predators. Therefore, the word "amphibian" signifies this dual life and their incredible adaptability to different ecosystems.