Because it carries a lot of blood to the arteries
If the stimulus reaches the threshold an action potential will be generated. If the stimulus doesn't reach it no action potential will be generated. If the stimulus will be stronger the action potential will have the same amplitude. The refractory period makes it harder to generate an action potential so they decrease the frequency of action potential production.
Answer;
C) decreasing the concentration of an enzyme
Explanation;
-Environment factors such as temperature and pH affects the activity of an enzyme. Changing these conditions alters the rate of the reaction caused by the enzyme.
-Each enzyme works at certain optimal conditions such as optimal temperature and optimal pH, thus increasing temperature and pH to optimal levels will increase the rate of enzyme reaction.
-Changing the concentration of enzyme and substrate will also affect the rate of reaction of an enzyme-catalyzed reaction. Increasing enzyme concentration increases the rate of enzyme activity.
Sunlight because that’s what they need to live