- The neuroeffector junctions of the sympathetic nervous system primarily utilize adrenergic receptors to mediate their responses.
- When sympathetic postganglionic neurons release neurotransmitters, the predominant neurotransmitter is norepinephrine (except in some cases like sweat glands, which use acetylcholine).
- This norepinephrine acts on alpha (α) and beta (β) adrenergic receptors located on the target effector cells such as smooth muscle, cardiac muscle, and glands.

- The alpha adrenergic receptors (α₁ and α₂) are mainly involved in vasoconstriction, increased peripheral resistance, and other excitatory effects.
- The beta adrenergic receptors (β₁, β₂, β₃) mediate responses such as increased heart rate (β₁), bronchodilation (β₂), and lipolysis (β₃).

- In contrast, muscarinic and nicotinic cholinergic receptors are associated with the parasympathetic nervous system and the autonomic ganglia respectively, and dopaminergic receptors play roles in certain specific pathways but are not the primary receptors at sympathetic neuroeffector junctions.

Therefore, the correct answer is that alpha and beta adrenergic receptors mediate responses at the neuroeffector junctions of the sympathetic nervous system.

Reference: Ganong's Review of Medical Physiology, 26th Edition, Chapter 15: Autonomic Nervous System and Adrenal Medulla