Final answer:
Anaphylaxis is a severe allergic reaction, falling under the topic of Integumentary in Biology.
Step-by-step explanation:
The subject of this question is Allergy - Anaphylaxis, which falls under the topic of Integumentary in Biology. Anaphylaxis is a severe allergic reaction that can occur in response to allergens such as certain foods, insect stings, or medications. It is characterized by symptoms such as swelling, difficulty breathing, hives, and a drop in blood pressure.