<prompt> Arrange the following opioids according to their potency most potent first a. Fentanyl b. Sufentanil c. Morphine d. Pethidinea,d,c,bb,a,c,da,d,b,cb,c,d,a  <response>: a. Fentanyl group of opioids are most potent opioids. Among these most potent is Sufentanil approx 1000 times more potent than morphine . The sequence of potency from high to low in this group is Sufentanil Fentanyl Alfentanil. b. Pethidine is 10 times less potent than morphine 