This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
100 % bioavailability is seen with which route 
Select and explain. 
A. Oral, B. Intravenous, C. Rectal, D. Subcutaneous
B: Intravenous
Answer: B: Intravenous 
Explanation: • 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
■ The incomplete extent of absorption
■ First pass metabolism
Routes of Administration, Bioavailability, and General Characteristics