A 50-year-old obese wom an w ith type 2 diabetes was found to have inadequate control of her disease 2 m onths after starting therapy w ith m etform in and glyburide. The physician decided to add exenatide to the treatm ent regim en. Which of the follow ing m olecular actions m ost likely m ediated the therapeutic e ect of the added drug in the patient’s disease? A. Inhibition of dipeptidyl peptidase-4 B. Inhibition of a-glucosidase C. Activation of adenosine m onophosphate (AMP)-activated protein kinase D. Activation of glucagon-like polypeptide-1 (GLP-1) receptors E. Activation of adenosine triphosphate (ATP)-sensitive K+ channels F. Phosphorylation of tyrosine kinase receptor