All of the Following About Oral Drug Absorption Is True

All of the following about oral drug absorption is true EXCEPT:

A) The most variable route of administration
B) The most complicated of administration
C) Duodenum is the major site of entry to the systemic circulation
D) Most drugs absorbed from the gastrointestinal tract enter directly the systemic circulation
E) First-pass metabolism by the liver limits the efficacy of many drugs.