Which Type of Experimental Evidence Shows That the Intrinsic GTPase

Which type of experimental evidence shows that the intrinsic GTPase activity of the Gα subunit is important for terminating effector activation?

A) A nonhydrolyzable GTP analog that can bind to the Gα subunit but cannot be hydrolyzed by the intrinsic GTPase,thereby activating the effector protein longer upon ligand-induced activation of the receptor.
B) A nonhydrolyzable GTP analog causes displacement of GDP with the modified GTP resulting in continuous activation of the receptor because the bound GTP analog cannot be hydrolyzed to GDP.
C) A dominant active (constant activity) GEF causes stimulation of the effector protein for longer upon ligand-induced activation of the receptor.
D) A dominant negative (no activity) GEF causes stimulation of the effector protein for longer upon ligand-induced activation of the receptor.