question: Q:A researcher is studying receptors that respond to epinephrine in the body and discovers a particular subset that is expressed in presynaptic adrenergic nerve terminals. She discovers that upon activation, these receptors will lead to decreased sympathetic nervous system activity. She then studies the intracellular second messenger changes that occur when this receptor is activated. She records these changes and begins searching for analogous receptor pathways. Which of the following receptors would cause the most similar set of intracellular second messenger changes?? 
  {'A': 'Aldosterone receptors in the kidney', 'B': 'Dopamine receptors in the brain', 'C': 'Growth hormone receptors in the musculoskeletal system', 'D': 'Muscarinic cholinoreceptors in the gastrointestinal tract', 'E': 'Vasopressin receptors in the kidney'},