Final answer:
At six months of age, infants can usually pull themselves into a sitting position independently as part of their physical development.
Step-by-step explanation:
At six months of age, an infant is typically able to pull themselves into a sitting position independently. This is a major milestone in their physical development as they gain better control over their muscles. It is important to note that each child develops at their own pace, so there may be some individual variation in achieving this skill.