Step-by-step explanation:
a) Second messengers are intracellular signalling molecules produced by the cell in response to exposure to extracellular signalling molecules. Second messengers serve to transmit signals from a receptor to a target inside the cell. They also serve to amplify the strength of the signal.
b) Cyclic AMP (cAMP) and Calcium ions.
c) cAMP is involved in cAMP dependent pathway also known as adenylyl cyclase pathway. It is a signalling cascade that involves G protein coupled receptor that is used in cell communication.
Calcium ions are involved in phospholipase C pathway.