Which of the following second messengers is generated from guanosine triphosphate?

The correct answer is cyclic GMP, which is a second messenger generated from guanosine triphosphate (GTP). In the signaling pathways of cells, the enzyme guanylate cyclase catalyzes the conversion of GTP to cyclic GMP. This cyclic GMP acts as a crucial secondary messenger involved in various physiological processes, such as vasodilation, signal transduction, and the modulation of ion channels.

Cyclic AMP is generated from adenosine triphosphate (ATP) and not from GTP, so it is not the correct answer. Diacylglycerol and inositol triphosphate are products of phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis, which is another signaling pathway distinct from that involving GTP. These pathways utilize different primary molecules and enzymes, highlighting the specificity in cellular signaling mechanisms. Thus, cyclic GMP remains the only correct answer as directly derived from GTP.