Answer:
b. adenosine triphosphate (ATP) is not a common intracellular secondary messenger.
Explanation:
Intracellular second messenger molecules are released in response of exposure to extracellular signalling molecules. Examples are inositol 1,4,5-trisphosphate (IP3) , adenosine monophosphate (AMP) ,1,2 diacylglycerol (DAG) , 3'-5' cyclic guanine monophosphate (cGMP)