**Core Concept**
The Tonic Labyrinthine Reflex (TLR) and Tonic Neck Reflex (TNR) are two primitive reflexes that are present in infants. These reflexes are mediated by the vestibular system and are crucial for the development of balance and spatial orientation. The Tonic Neck Reflex is typically seen in infants as a response to lateral flexion of the neck, where the arm on the same side as the flexion extends and the opposite arm flexes.

**Why the Correct Answer is Right**
The Tonic Neck Reflex is not prominent in a child at birth because it is a reflex that typically emerges around 2-3 months of age, as the infant's brain and nervous system mature. This reflex is essential for the development of hand-eye coordination and spatial awareness, but it is not present at birth. In contrast, Moro's reflex, Glabellar tap, and Crossed extensor reflex are all present at birth and play a crucial role in the infant's development and adaptation to their environment.

**Why Each Wrong Option is Incorrect**
**Option A:** Moro's reflex is a fundamental reflex present at birth, characterized by a wide-eyed, open-mouthed response to a sudden loss of support. It is a critical reflex for the infant's adaptation to the environment.
**Option B:** Glabellar tap reflex is a response to a gentle tap on the glabella, where the infant's eyes blink in response. This reflex is present at birth and is an important indicator of the integrity of the afferent and efferent pathways of the trigeminal nerve.
**Option C:** Crossed extensor reflex is a reflex that is present at birth, where the infant's arm and leg on the opposite side of the stimulus extend. This reflex is an important indicator of the development of the motor systems and is a precursor to the more complex movements seen in older infants.

**Clinical Pearl / High-Yield Fact**
Primitive reflexes, such as the Tonic Neck Reflex, are essential for the development of motor skills and spatial awareness in infants. These reflexes typically emerge and disappear at specific ages, and their presence or absence can be used as an indicator of normal or abnormal development.

**✓ Correct Answer: D. Tonic neck reflex**