What milestone is typically reached when infants are aged 12-15 months?

Infants typically reach the milestone of walking independently between the ages of 12 and 15 months. This developmental stage is significant because it signifies an increased level of physical ability and independence. Walking independently allows infants to explore their environment in new ways, fostering cognitive development and spatial awareness. During this period, many children take their first steps without support, often showing enthusiasm and determination as they practice this newfound skill.

While other options represent developmental milestones that may occur earlier or later, walking independently is uniquely characteristic of the specified age range. Creeping on all fours generally occurs much earlier, typically around 8 to 12 months, and walking with assistance is a transitional phase that leads to independent walking. Protective extension laterally, which involves reaching out to the side to prevent falls, is usually observed in toddlers who are becoming more confident in their movements but does not specifically align with the 12-15 month period as the primary milestone.