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
All of the following use c-AMP as a second messenger except 
Select and explain. 
A. Coicotropin, B. Dopamine, C. Testosterone, D. Vasopressin
C: Testosterone
Answer: C: Testosterone 
Explanation: Testosterone - the principal male sex hormone (androgen) is a steroid hormone that is produced by Leydig&;s cells of the testes in response to luteinizing hormone secreted by the pituitary gland. It is also produced by the adrenal coex in both males and females.Ref: Ganong&;s review of medical physiology; 24th edition: page no: 423