Developmental Milestone - 6 Month Old Infant

As a nurse in a pediatric clinic, you are conducting a developmental assessment on a 6-month-old infant during a routine well-child visit. You note that the infant is able to sit without support, babbles with varying intonations, and reaches for objects in their environment. Based on your observations, which of the following milestones should be the next anticipated developmental achievement for this infant in the coming months?