Camp activates camp-dependent protein kinase by
bindingregulatory subunits and inducing their release from the
catalyticsubunits.
stimulating itsphosphorylation.
stimulating thedimerization of kinase subunits.
stimulating therelease of a translational inhibitory protein
bound to itsmrna.

binding regulatory subunits and inducing their release from the  catalytic subunits

Explanation:

cAMP molecules diffuse into the cytoplasm where they bind to an allosteric site on a regulatory subunit of a cAMP-dependent protein kinase ( protein kinase A,  PKA).

-In its inactive form, PKA is a  heterotetramer comprised of two subunits namely, regulatory (R) and two catalytic (C) subunits.

-The regulatory subunits normally inhibit  the catalytic activity of the enzyme. cAMP binding causes the  dissociation of the regulatory subunits, thereby releasing the  active catalytic subunits of PKA.

-cAMP stimulates glucose mobilization by  activating a protein kinase that adds a phosphate group  onto a specific serine residue of the glycogen phosphorylase  polypeptide.

the answer is c. altitude. hope this ! #brainiac