<prompt> Variation in the sensitivity of a population of individuals to increasing doses of a drug is best determined by which of the followingEfficacyPotencyTherapeutic indexQuantal dose -response  <response>: D. i.e. Quantal dose - response curve 34- Lippincotss 4thOnly a quantal dose - response curve gives information about differences in the sensitivity of individuals to increasing doses of a drug ED50 is a measure of potencyEFFICACY Intrinsic activity - determined from graded dose response plotsEfficacy is more important than drug potency. A drug with greater efficacy is more therapeutically beneficial than one that more potentTHERAPEUTIC INDEX TD50ED50 is a measure of a drugs safety. Because a larger value indicates a wide margin between doses that are effective an doses that are toxic 