This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
Following organ/tissue have proven endocrine function/capability except 
Select and explain. 
A. Hea, B. Adipocytes, C. Stomach, D. Salivary gland
D: Salivary gland
Answer: D: Salivary gland 
Explanation: Salivary gland secretes only saliva all other organs has endocrine functionRef: Ganong&;s review of medical physiology; 24th edition