Central Mechanisms Cause Contraction and Increased Resistance to Blood Flow $\alpha$

Central mechanisms cause contraction and increased resistance to blood flow mainly through which of the following?

A) adrenergic stimulation and the release of norepinephrine
B) cholinergic stimulation and the release of acetylcholine
C) cholinergic stimulation and the release of norepinephrine
D) stimulation of specialized $\alpha$ -adrenergic receptors