Child rolls over by
**Core Concept**
The question is testing the developmental milestone of rolling over in infants, which is a significant achievement in their motor skills development. Rolling over is a precursor to other motor skills such as crawling, standing, and walking. It is an essential milestone in the gross motor development of infants.
**Why the Correct Answer is Right**
Rolling over is a skill that infants typically develop around 4-6 months of age. It involves the coordination of the neck and back muscles, as well as the development of sufficient strength and flexibility in these areas. As the infant gains more control over their body, they learn to roll over from their stomach to their back and vice versa. This skill is an important indicator of normal motor development in infants.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not provide a valid answer choice for the question.
**Option B:** This option is incorrect as it does not provide a valid answer choice for the question.
**Option D:** This option is incorrect as it does not provide a valid answer choice for the question.
**Clinical Pearl / High-Yield Fact**
It is essential for pediatricians and healthcare providers to assess the motor skills of infants regularly, as delayed or absent rolling over can indicate underlying developmental issues or neurological disorders.
**Correct Answer: D. 4-6 months of age**