Final answer:
An optimal environment for promoting the physical development of infants is one that allows for outdoor play. Outdoor play provides children with opportunities to experience the world, collect objects, and develop lifelong interests.
Step-by-step explanation:
An optimal environment for promoting the physical development of infants is one that allows for outdoor play. Outdoor play provides children with opportunities to experience the world, collect objects, and develop lifelong interests. It also promotes exercise and a healthy heart and brain. Unfortunately, research suggests that children today engage in less outdoor play, which contributes to childhood obesity. Therefore, it is important to encourage outdoor play to support infants' physical development.