<span>Fifty percent of the gases that make up the atmosphere are found below 5.6 kilometers in the atmosphere. As height increases the density of gasses is lowered until you finally exit the atmosphere and enter a vacuumous space.</span>
Answer:
B) cAMP
Explanation:
Phosphodiesterase is an enzyme that breaks a phosphodiester bond, for example in molecules such as cAMP and cGMP. So, phosphodiestarases are are regulators of signal transduction: regulate the duration of signaling pathway.
Caffeine is central-nervous-system stimulant and the mechanisms of its action usually are: mobilization of intracellular calcium or inhibition of specific phosphodiesterases.