Parasympathetic activation would _________ heart rate while sympathetic activation would ______ heart rate.

• A. Increase; decrease.
• B. Not affect; increase.
• C. Decrease; not affect.
• D. Decrease; increase.

Answer: (D)

Verified step by step guidance

1. Understand the role of the autonomic nervous system, which is divided into the sympathetic and parasympathetic nervous systems, in regulating involuntary body functions.
2. Recognize that the sympathetic nervous system is responsible for the 'fight or flight' response, which prepares the body for action by increasing heart rate, among other effects.
3. Identify that the parasympathetic nervous system is responsible for the 'rest and digest' response, which conserves energy by slowing down the heart rate and promoting relaxation.
4. Apply this knowledge to the problem: parasympathetic activation would decrease heart rate as it promotes relaxation and energy conservation.
5. Similarly, sympathetic activation would increase heart rate as it prepares the body for action and heightened alertness.