Which of the following must be included in infant rooms?

Infant rooms are designed to provide a safe, engaging, and developmentally appropriate environment for young children. One of the fundamental requirements for these spaces is the inclusion of indoor play materials. These materials, such as soft toys, stacking blocks, and sensory items, support the cognitive, physical, and social development of infants. They encourage exploration, help in developing motor skills, and stimulate curiosity, all of which are crucial at this stage of development.

The other options do not serve the primary needs of an infant room in the same way. Outdoor play equipment, while beneficial for older children, is not suitable for infants due to safety concerns and the nature of their developmental needs. Books for parents provide valuable information but do not directly serve the infants themselves; they focus more on parental education than on creating an engaging atmosphere for infants. Couches for rest might offer comfort for caregivers but are not a necessary component for the infants' environment, as proper sleeping areas designed specifically for infants are more critical. Thus, the inclusion of indoor play materials is essential for fostering a supportive and enriching environment for infants.