Question

autonomic tone is important because it
provides for a narrow range of control options that keeps target tissues constantly active.
allows ans neurons to increase or decrease their activity.
allows ans neurons to be silent under normal conditions.
allows ans neurons to decrease their activity on demand but not increase their activity.
allows ans neurons to increase activity on demand but not decrease their activity.

Explanation:

Autonomic tone refers to the balance between sympathetic and parasympathetic activity in the autonomic nervous system (ANS). It allows for a dynamic range of control. If the tone was such that neurons could only increase or only decrease activity (options 4 and 5), or be silent (option 3), or have a narrow range (option 1), it would not provide the flexibility needed for the body's responses. The ANS needs to be able to adjust its activity (increase or decrease) based on the body's needs (e.g., increasing heart rate during exercise - sympathetic activation; decreasing it during rest - parasympathetic activation).

Answer:

allows ANS neurons to increase or decrease their activity.