## Core Concept
The Moro reflex, also known as the startle reflex, is a natural reflex found in newborns. It is characterized by a specific response to a perceived threat or sudden loss of support, involving the extension and then flexion of the arms. This reflex is an important indicator of the neurological development and integrity of infants.

## Why the Correct Answer is Right
The Moro reflex typically appears at birth and disappears by the time the infant is about 4 to 6 months old. This timeframe is crucial for neurological development, and the disappearance of the Moro reflex is a significant milestone. It indicates the maturation of the infant's nervous system, particularly the development of the cerebral cortex, which eventually suppresses this primitive reflex.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests the Moro reflex disappears at birth, which is incorrect because the reflex is present at birth and does not disappear immediately.
- **Option B:** This option might suggest an earlier disappearance (e.g., 2 months), which is too early for the Moro reflex to typically disappear.
- **Option D:** This option might suggest a later disappearance (e.g., 12 months), which is generally too late for the Moro reflex to disappear in a normal infant.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the persistence of the Moro reflex beyond 6 months of age can be an indicator of neurological impairment or developmental delay. Clinicians often assess for the presence or absence of this reflex during routine infant check-ups to monitor neurological development.

## Correct Answer: C. 4-6 months.