**Core Concept**
The calculation of total body surface area (TBSA) burnt in children follows the **Rule of Nines**, adjusted for pediatric patients. Unlike adults, children have a larger head and smaller legs, so the standard adult Rule of Nines is modified. The buttocks, both legs, face, and neck are all significant burn zones, and singeing of hair indicates a facial burn, which is included in the calculation.

**Why the Correct Answer is Right**
In a 2-year-old child, the Rule of Nines is adjusted as follows:
- Face and neck: 9%
- Each leg: 13.5% (so both legs = 27%)
- Buttocks: 1% (each buttock is 1% in pediatric Rule of Nines)
- Total: 9% (face/neck) + 27% (legs) + 1% (buttocks) = **37%**
Singeing of hair confirms facial involvement, which is already accounted for. This aligns with the pediatric Rule of Nines, where the head/neck is 18%, but face/neck is 9%, and legs are 13.5% each.

**Why Each Wrong Option is Incorrect**
Option A: 27% – This is the sum of both legs only, missing face, neck, and buttocks.
Option C: 45% – This overestimates the burn area; it may include a full body or misapplies the Rule of Nines.
Option D: 55% – This is far beyond the pediatric TBSA limit and would require major burns involving trunk and arms, which are not mentioned.

**Clinical Pearl / High-Yield Fact**
In children, **face and neck** are included in the **9% face/neck** category, and **buttocks** are **1%** each. Always use the pediatric Rule of Nines—never the adult version—especially in young children where proportions differ significantly.

✓ Correct Answer: B. 37%