**Core Concept**
In pediatric patients, daily water requirement is estimated using body surface area (BSA) or weight-based formulas. The standard formula for total daily fluid needs in children is approximately **30–35 mL/kg/day** of body weight, with BSA-based adjustments used in specific clinical contexts like burns or dehydration.

**Why the Correct Answer is Right**
For a child weighing 30 kg, the water requirement using the standard pediatric formula is 30 mL/kg/day × 30 = 900 mL/day. However, the question specifies BSA of 1 m², which is a key indicator of surface area. In pediatric fluid management, a commonly used rule is that **daily water requirement is approximately 1700 mL for a child with BSA of 1 m²**. This aligns with the modified formula: **1700 mL per m² of BSA** in children, which accounts for metabolic rate, body composition, and fluid distribution differences from adults.

**Why Each Wrong Option is Incorrect**
Option A: 1300 mL is too low and underestimates the actual requirement based on standard pediatric fluid needs.
Option C: 2000 mL exceeds the typical range and may suggest overestimation, especially without clinical indication.
Option D: 2500 mL is excessively high and not consistent with standard pediatric fluid guidelines.

**Clinical Pearl / High-Yield Fact**
In pediatrics, **1700 mL/day per m² BSA** is a reliable estimate for daily water requirement in children, especially in clinical settings where weight or height is unavailable. Always remember: **BSA-based fluid needs are more accurate than weight-based in complex cases**.

✓ Correct Answer: B. 1700 ml