What is a major effect of vascular activity during SNS activation?

The correct answer indicates that during sympathetic nervous system (SNS) activation, vasoconstriction occurs, leading to reduced blood flow to the hands and fingers. When the SNS is activated, typically in a fight-or-flight situation, the body prioritizes blood supply to vital organs and muscles to prepare for immediate physical activity. This response involves the constriction of blood vessels in less critical areas, such as the extremities, which can result in decreased circulation to the hands and fingers.

This physiological response is essential for survival during acute stress, as it ensures that the body can react swiftly to threats by optimizing blood flow to the muscles and organs that are most critical for defense or escape. The other options present a misunderstanding of SNS activation; they either imply a positive increase in blood flow to areas that would actually see a decrease or suggest improvements in dexterity or general circulation, which run counter to the body's protective mechanisms during high-stress situations.