Which statement best describes a difference between how the sympathetic and parasympathetic nervous system affects the heart?

• A. The sympathetic nervous system affects heart rate, while the parasympathetic nervous system affects contractility.
• B. The sympathetic nervous system affects contractility and heart rate, while the parasympathetic only affects heart rate.
• C. Both the sympathetic and parasympathetic nervous systems affect contractility, while the parasympathetic also affects heart rate.
• D. Heart rate is controlled by the parasympathetic nervous system, while the sympathetic nervous system controls contractility.