The correct answer is option 4: volant. Animals adapted to life in the air are referred to as volant. This term is commonly used to describe animals that have developed wings or other structures that enable them to fly or glide through the air. Examples of volant animals include birds, bats, and insects. These animals have evolved various adaptations such as strong and lightweight bones, feathers, or wings, that allow them to maneuver and travel in the air. Option 1, fossorial, refers to animals adapted to living underground. Option 2, arboreal, describes animals that live in trees. Option 3, cursorial, refers to animals adapted for running.