Which of the following is influenced by the activation of the sympathetic nervous system?

The activation of the sympathetic nervous system is primarily associated with the body's "fight or flight" response, which prepares the body to react to perceived threats. One of the physiological changes that occur during sympathetic activation is an increase in heart rate. This rise in heart rate helps pump more blood to muscles and vital organs, enhancing the body's ability to respond quickly to stress or danger.

In contrast, decreased blood pressure, enhanced digestion, and increased salivation are generally associated with the activation of the parasympathetic nervous system, which promotes a state of rest and recuperation. Enhanced digestion and increased salivation are particularly linked to calming responses rather than the heightened activity characteristic of the sympathetic nervous system. Thus, the correct answer signifies a clear understanding of the roles played by the sympathetic nervous system in physiological responses during stress.