<h2>Answer</h2>
The parasympathetic neurotransmitter at target organs is <u>acetylcholine</u><u>.</u>
<h3>#CarryOnLearning</h3>

 
 
        
        
        
The correct answer for this question is: "<span>B) kidneys clean the blood by filtering it to remove wastes." Kidneys clean the blood by filtering it and removing the waste.
The correct answer for this question is: "</span><span>A) secretes excess water as sweat." The role of the skin in the excretory system is to secrete waste and excess water as sweat.</span>
        
                    
             
        
        
        
The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
 
        
             
        
        
        
Explanation:
they are all related to CO2 in a way
 
        
             
        
        
        
B cause they all blend in with snow so they can survive