## Core Concept
The question pertains to the equipment used in neonatal resuscitation, specifically the volume of the reservoir bag. In neonatal resuscitation, a self-inflating bag or a T-piece resuscitator may be used, but the focus here is on the reservoir bag which is often used with a T-piece resuscitator. The reservoir bag is crucial for providing a consistent and controlled flow of gas to the newborn.

## Why the Correct Answer is Right
The correct volume of the reservoir bag used in neonatal resuscitation is **600 mL**. This volume is chosen because it allows for adequate tidal volumes to be delivered to newborns during resuscitation efforts without causing excessive pressure that could lead to lung injury. The 600 mL reservoir bag is designed to be used with a T-piece resuscitator and is a standard component of neonatal resuscitation equipment.

## Why Each Wrong Option is Incorrect
- **Option A:** 300 mL - This volume might be too small for effective resuscitation, potentially leading to inadequate tidal volumes.
- **Option B:** 1000 mL - This volume could potentially deliver too high tidal volumes, increasing the risk of lung injury in a newborn.
- **Option D:** 200 mL - Similar to option A, this volume is likely too small for effective neonatal resuscitation.

## Clinical Pearl / High-Yield Fact
A key point to remember is that during neonatal resuscitation, the use of a **600 mL reservoir bag** is recommended for term infants. It's also crucial to be aware of the pressures used during resuscitation to avoid barotrauma. The American Academy of Pediatrics and other neonatal resuscitation guidelines often provide specifics on the equipment to be used.

## Correct Answer Line
**Correct Answer: C. 600 mL.**