To secrete within the blood or the endocrine system.

• A. Endocrine
• B. Endocrinologist
• C. Endoderm
• D. Endometriosis

Answer: (A)

Endocrine describes glands that secrete hormones directly into the bloodstream, circulating through the blood to regulate distant organs. The term comes from endo- meaning within and crine meaning to secrete, highlighting secretion inside the body’s hormonal system. This distinguishes it from exocrine glands, which release substances through ducts to outside the body or into a hollow organ. The other terms aren’t about secretion into the blood: an endocrinologist is a doctor who treats endocrine disorders, endoderm is a germ layer in early development, and endometriosis is a condition where endometrial-like tissue grows outside the uterus.