The correct option is D both a and b are correct
Autonomic neural system is the system of peripheral motor or efferent nerve fibres and ganglia which innervate various visceral organs and glands of the body.
It stimulates, accelerates, slows down or inhibits function of organs and glands of the body itself without the will of the body. Because the autonomic system controls involuntary activities of various visceral organs and glands, it is also called visceral neural system and involuntary neural system.