Activation of the sympathetic nervous system causes:

a. increased blood flow into the skin

b. a decreased heart rate

c. an increased heart rate

d. increased digestion

The sympathetic nervous system is a component of the autonomic nervous system, a large neural network. It is in charge of controlling the body's involuntary processes. It gets someone ready for an unexpected emergency. It primarily becomes active when there is a threat of an attack or when you are apprehensive about something.

In times of emergency, the sympathetic nervous system gets the body ready for the "fight or flight" reaction. Through a network of connected neurons, the sympathetic nervous system functions. Adrenaline and noradrenaline are two catecholamines that are released by the sympathetic nervous system to stimulate the adrenal gland. The "fight or flight response" can happen in any emergency or dangerous situation. Emergency situations can cause bodily symptoms like a rapid heartbeat.

Increased blood flows into the skin, increased digestion and a decreased heart rate are responses to the activation of the parasympathetic nervous system and thereby, the Rest of the options became irrelevant to the question.