Which of the following factors can influence drug absorption?

The influence of drug formulation and route of administration on drug absorption is significant, and this is why it is the correct answer. The formulation of a drug—such as whether it is a tablet, capsule, liquid, or injectable—determines how quickly and efficiently it can be absorbed into the bloodstream. For example, liquid formulations often have a faster absorption rate compared to solid forms due to their ability to bypass certain phases of digestion.

Additionally, the route of administration—such as oral, intravenous, intramuscular, or subcutaneous—greatly impacts absorption. Intravenous drugs enter directly into the bloodstream, allowing for immediate effects, while oral medications must go through the gastrointestinal tract, which can delay absorption due to various factors such as stomach contents, pH level, and gastrointestinal motility. Thus, both the drug formulation and the chosen route are crucial in determining how effectively a drug will be absorbed by the body.