Which one of the following could indicate concern for a three-month-old's development?

At three months of age, certain developmental milestones are expected as a part of typical growth patterns. The ability to grasp objects is one of those milestones that typically emerges around this age. Infants usually begin to show a reflexive grasp that can develop into more purposeful handling of objects as they approach four to five months of age.

If a three-month-old cannot grasp objects, it may indicate a developmental delay or concern. This is significant because the ability to grasp is not only an indication of motor development but also plays a role in sensory exploration and cognitive development as infants begin to interact with their environment. In contrast, smiling at others, lifting the head, and making cooing sounds are all milestones that are typically achieved by this age, and thus would not generally raise concerns.