Biology

The correct answer is D. Immune.

The immune system is the body's defense against attack from pathogens, such as bacteria, viruses, and other harmful microorganisms. It is responsible for recognizing and eliminating foreign substances, toxins, and abnormal cells in order to protect the body from infections and diseases.

Option A, the endocrine system, is responsible for producing and releasing hormones that regulate various bodily functions. While hormones can influence immune responses, the endocrine system as a whole is not primarily responsible for defending against attacks.

Option B, the excretory system, is responsible for filtering the blood, removing ...