**Core Concept**
The question tests the understanding of **Total Body Surface Area (TBSA)** burned, which is crucial in assessing the severity of burns. The **Lund and Browder chart** or **Wallace rule of nines** are commonly used methods to estimate TBSA. However, for children, the **Lund and Browder chart** is more accurate due to the varying proportions of body parts at different ages.

**Why the Correct Answer is Right**
Given the areas involved - face including scalp, both buttocks, and circumferentially around both thighs, we can estimate the TBSA using the **Lund and Browder chart**. The face and scalp account for about 18% of TBSA in a 3-year-old, buttocks about 5%, and each thigh about 6.5% (considering the circumferential involvement, this would account for both the front and back of the thighs, so approximately 13% for both thighs). Adding these percentages gives an approximate TBSA involvement.

**Why Each Wrong Option is Incorrect**
**Option A:** This option would underestimate the TBSA involved, not accounting for the full extent of the burns.
**Option B:** This option might overestimate or not accurately reflect the TBSA based on the described burn areas.
**Option D:** Similarly, this option does not accurately represent the calculated TBSA based on the areas burned.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that in pediatric patients, the proportions of body parts change with age, making the **Lund and Browder chart** particularly useful for estimating TBSA accurately in this demographic. The proportions of body surface area change significantly from infancy through childhood.

**Correct Answer:** C. 36%