**Core Concept**
Circulatory collapse in burn patients is related to the **total body surface area (TBSA)** affected by burns, which leads to **hypovolemic shock** due to fluid loss. The extent of burns is a critical factor in determining the severity of the injury and the risk of circulatory complications.

**Why the Correct Answer is Right**
The correct answer is related to the percentage of TBSA burned, which correlates with the risk of circulatory collapse. Burns affecting a large percentage of TBSA can lead to significant fluid loss, resulting in **hypovolemia** and decreased **cardiac output**.

**Why Each Wrong Option is Incorrect**
**Option A:** This option underestimates the percentage of TBSA that can lead to circulatory collapse.
**Option B:** This option also underestimates the risk.
**Option D:** Overestimates the percentage, as circulatory collapse can occur with less severe burns.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that burns affecting more than 15% of TBSA in adults can lead to severe fluid loss and circulatory instability, necessitating aggressive fluid resuscitation.

**Correct Answer:** C. 15%