After teaching a class about the endocrine system, the instructor determines that the students need additional instruction when they identify which of the following as an endocrine gland?
A)
Pancreas
B)
Adrenal gland
C)
Testes
D)
Kidneys

The correct answer is D)  Kidneys

Explanation:

The endocrine system contains the glands which secrete their secretion called hormone directly in the blood because their target organs are situated distantly from them where the hormone reach through blood.

Pancreas, adrenal gland, and testes are the endocrine glands which secrete hormones directly in the blood. The kidney is not an endocrine gland and does not secrete any hormone. The kidney is responsible for filtering blood and removal of nitrogenous and other waste from the body. Therefore the correct answer is D.