## **Core Concept**
The question assesses the ability to calculate the percentage of body surface area (BSA) affected by burns, specifically using the "Rule of Nines" for adults. This rule is a method for estimating the size of a burn injury. The **Rule of Nines** assigns a percentage value to different body parts: head and neck (9%), each upper limb (9%), front and back of torso (18% each), each leg (18%), and genitalia (1%).

## **Why the Correct Answer is Right**
The correct answer, **B. 18%**, is based on the "Rule of Nines." Each upper limb accounts for 9% of the BSA. Since both upper limbs are scalded, the total percentage of burns is 9% + 9% = 18%. This method provides a quick and reasonably accurate estimation of the extent of burn injuries.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 9% - This option is incorrect because it only accounts for one upper limb, not both.
- **Option C:** 27% - This option is incorrect because it suggests an additional 9% that isn't accounted for by the two upper limbs alone; it might mistakenly include the head or another body part.
- **Option D:** 36% - This option is incorrect as it would imply 4 limbs (4 * 9% = 36%), which is not the case here.

## **Clinical Pearl / High-Yield Fact**
A crucial point to remember is that the **"Rule of Nines"** is specifically designed for adults. For children, a different method, such as the **Lund-Browder chart**, is used because the proportion of body surface areas changes with age. Always consider the patient's age when assessing burns.

## **Correct Answer: B. 18%.**