Which one of the following acts as second messenger?

Ans. is 'c' i.e. Ca++ Second messengers are molecules that relay signals received at receptors on the cell surface (such as the arrival of protein hormones, growth factors, etc.) to target molecules in the cytosol and/or nucleus.Not only they relay the signals, they greatly amplify the strength of the signal.There are three major classes of second messengers.cyclic nucleotides (e.g. cAMP & cGMP)products of membrane phospholipid breakdown-inositol triphosphate (1P3) and diacyl glycerol (DAG)calcium ionsCalcium ions are probably the most widely used second messengers.