Oxytocin, insulin, and vasopressin are all proteins, and they all coordinately regulate metabolic functions in several tissues. How else are they related, biochemically?
(A) They all increase glucose storage, but in different tissues
(B) They all act on different tissues but all signal through tyrosine kinase receptors.
(C) They are all released by the same endocrine tissue but bind to different receptors.
(D) They are all very small and contain internal disulfide linkages.
(E) They are all endocrine hormones that have similar signaling effects on target tissues.