## Core Concept
The question tests the understanding of intravenous (IV) fluid maintenance dose calculation in pediatric patients. The **maintenance fluid requirement** is based on the **Holliday-Segar formula**, which estimates the daily fluid needs for children.

## Why the Correct Answer is Right
The Holliday-Segar formula for calculating maintenance fluids in children is as follows:
- For the first 10 kg of body weight: 100 mL/kg/day
- For the next 10 kg of body weight (11-20 kg): 50 mL/kg/day
- For weight above 20 kg: 20 mL/kg/day

Given the child weighs 25 kg:
- For the first 10 kg: 100 mL/kg * 10 kg = 1000 mL/day
- For the next 10 kg (11-20 kg): 50 mL/kg * 10 kg = 500 mL/day
- For the remaining 5 kg (above 20 kg): 20 mL/kg * 5 kg = 100 mL/day

Total = 1000 mL/day + 500 mL/day + 100 mL/day = 1600 mL/day

To find the hourly rate: 1600 mL/day / 24 hours = approximately 66.67 mL/hour.

## Why Each Wrong Option is Incorrect
- **Option A:** Significantly underestimates the fluid requirement based on the child's weight.
- **Option B:** Also underestimates; precise calculation yields a higher value.
- **Option D:** Overestimates the fluid requirement according to the Holliday-Segar formula.

## Clinical Pearl / High-Yield Fact
A useful mnemonic to remember the rough estimates is: **4-2-1 rule** (for simplicity, not precise but helpful in emergencies):
- 4 mL/kg/hr for the first 10 kg
- 2 mL/kg/hr for the next 10 kg
- 1 mL/kg/hr for weight above 20 kg

For a 25 kg child: (4*10) + (2*10) + (1*5) = 40 + 20 + 5 = 65 mL/hr, which closely matches our calculation.

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