Violation
Bioavailability of orally administered drugs may be influenced by 1. formulation of the drug. 2. gastrointestinal perfusion. 3. pH of the gastrointestinal tract. 4. presence of other substances in the gastrointestinal tract.
All of the above.
(4) only
(2) and (4)
(1) and (3)
(1) (2) (3)