Which statement below best summarizes how G Protein Coupled Receptors function?

Group of answer choices

a. Ligand binding to the associated G protein will initiate the conversion of energy from GTP to GDP, thus activating the GPCR leading to a cellular response

b. Ligand binding to GPCR will activate an associated enzyme allowing for amplification of the signal leading to a cellular response

c. Ligand binding to the intracellular side of the GPCR will activate the associated G protein causing GTP to be converted to GDP thus allowing for amplification of the signal and a cellular response

d. Ligand binding to the extracellular side of the GPCR will inactivate the associated G protein causing GDP to be converted to GTP thus allowing for amplification of the signal and a cellular response