What is the significance of the discovery of different hormone receptor types for the hormone epinephrine?

• A. Two types of epinephrine hormone response elements were identified.
• B. Different tissues responded differently to the presence of epinephrine.
• C. It was discovered that slightly different forms of epinephrine (agonists) were secreted by the adrenal glands.
• D. All target tissues for epinephrine possess all four types of epinephrine receptors.