If a person suffered a burn that blistered the skin and required immediate medical attention, that person probably suffered what degree of burn?

The situation described involves a burn that blistered the skin and required immediate medical attention, which indicates that it is a second-degree burn. Second-degree burns affect both the outer layer of skin (epidermis) and part of the underlying layer (dermis). This type of burn is characterized by symptoms such as redness, swelling, pain, and blisters, which align with the details provided in the question.

First-degree burns only affect the outer layer of skin and usually result in redness and minor pain without blisters, making them less severe than what has been described. Third-degree burns penetrate deeper, destroying both the epidermis and dermis and potentially affecting underlying tissues; they often appear white, charred, or leathery and are less painful due to nerve damage. Fourth-degree burns extend even further into muscle and bone, which is much more severe than the injury described.

Therefore, the requirement for immediate medical attention due to blisters strongly indicates that the injury is a second-degree burn.