## Core Concept
Burns are classified based on their severity into different degrees, primarily first-degree, second-degree (also known as partial-thickness burns), and third-degree (also known as full-thickness burns) burns. The classification is based on the extent of damage to the skin layers.

## Why the Correct Answer is Right
Second-degree burns, also known as partial-thickness burns, affect both the epidermis and dermis layers of the skin. These burns are characterized by **blister formation** due to the separation of the epidermis from the dermis, which is a result of fluid accumulation. This type of burn typically presents with redness, swelling, and blisters, and the skin may be moist.

## Why Each Wrong Option is Incorrect
* **Option A:** First-degree burns only affect the **epidermis**, the outermost layer of the skin. They are characterized by redness, pain, and swelling but do not cause blister formation.
* **Option B:** Third-degree burns extend through all layers of the skin (**epidermis, dermis, and into the subcutaneous tissue**). These burns do not typically present with blisters because the dermis is completely destroyed, and the skin may appear white, leathery, or charred.
* **Option D:** While not explicitly defined here, the implication is that another option does not match the description of causing blister formation.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the presence of blisters is a hallmark of **second-degree burns**. This clinical feature helps in assessing the severity of burns and guides treatment, which may include wound care, dressing, and possibly surgical intervention.

## Correct Answer: C. Second-degree.