Which of the Following Experiments Provided Experimental Evidence That Potassium

Which of the following experiments provided experimental evidence that potassium channels in cardiac muscle cells were opened by the direct action of βγ-subunits of activated G proteins?

A) Cardiac potassium channels were opened in inside-out patch clamp recordings when pure recombinant α-subunit was applied to the intracellular side of the patch.
B) Cardiac potassium channels were opened in inside-out patch clamp recordings when pure recombinant βγ-subunit was applied to the intracellular side of the patch.
C) Removal of intracellular GTP prevents the activation of cardiac muscarinic receptors from opening of potassium channels.
D) The addition of intracellular Gpp(NH) p prolongs the opening of potassium channels after activation of cardiac muscarinic receptors.
E) Muscarinic receptor-mediated activation of potassium channels is blocked by pertussis toxin.