Which is true regarding the structure and synthesis of hormones? a. steroid hormones are synthesized from cholesterol. b. thyroid hormones are catecholamines. c. the hormones of the adrenal cortex have the same structure as the neurotransmitters of adrenergic neurons. d. most peptide hormones require binding proteins for transport in the blood. e. vasopressin is synthesized in the posterior pituitary?