A chemical signal that has both endocrine and neural roles is?

• melatonin

• calcitionin

• epinephrine

• cortisol

C.

epinephrine

Epinephrine secreted from the medulla of adrenal gland acts as both, an endocrine hormone and as a neurotransmitter (produced at the ends of sympathetic never fibres).
Epinephrine as hormone accelerates metabolic rate for preparing us to face emergency situations.
As neurotransmitter, it transmits nerve impulse across a synaptic left. Calcitonin is released when Ca²⁺ level increases, melatonin causes concentration of pigment in melanocytes and cortisol is a glucocorticoid.