A normal infant sits briefly leaning forward on her hands, reaches for and grasps a cube and transfer it from hand to hand. She babbles but can not wave bye–bye nor can she grasp objects with the finger and thumb. Her age is –
**Core Concept**
Developmental milestones in infants are crucial for assessing their cognitive, motor, and language skills. The question describes a set of skills that an infant typically achieves around a specific age, which is a key indicator of normal development.
**Why the Correct Answer is Right**
The described behaviors - sitting briefly, reaching for and grasping a cube, transferring it from hand to hand, babbling, but not waving bye-bye or grasping objects with the finger and thumb (pincer grasp) - are characteristic of an infant around 6-7 months of age. Infants at this stage are developing their gross motor skills, such as sitting up and transferring objects, but are still refining their fine motor skills, like grasping small objects with their thumb and index finger.
**Why Each Wrong Option is Incorrect**
* **Option A:** Infants typically achieve these milestones around 6-7 months, not 4-5 months, which is too early.
* **Option B:** The described behaviors are not typical of 8-9 months, as infants at this age usually exhibit more advanced fine motor skills, such as pincer grasp and waving bye-bye.
* **Option C:** The milestones described are not characteristic of 3-4 months, as infants at this age are still developing their gross motor skills and are not yet able to grasp objects or transfer them from hand to hand.
**Clinical Pearl / High-Yield Fact**
Remember the "Red Flags" for developmental delay: failure to sit up by 6-7 months, no crawling by 10-12 months, and no walking by 14-15 months. Early identification and intervention are crucial for optimal developmental outcomes.
**Correct Answer:** D. 6-7 months