100% bioavailability is seen with which route

(Ref: Katzung Pharmacology, 10th ed. Ch 3)Bioavailability is defined as the fraction of unchanged drug reaching the systemic circulation following administration by any route.In case a drug is given orally, the bioavailability shall be less than 100%. This is due to#Incomplete extent of absorption#First pass metabolismRoutes of administration, bioavailability, and general characteristicsRoute of AdministrationGeneralcharacteristicsBioavailabilityIntravenousOnset of action is fastest100%IntramuscularPainful75-100%SubcutaneousLesser volumes can be given compared to intramuscular route75-100%Per oralMost convenient from patients' perspective MC used route5% to <100%First pass metabolism limits blood levelsPer rectalLess first pass metabolism than peroral30 to <100%TransdermalVery slow absorption.Lack of first pass effectProlonged duration of action80-100%