Which of the following is a parenteral route of administration?

The parenteral route of administration refers to delivering medication directly into the body, bypassing the gastrointestinal tract. This method includes various techniques, such as injections that introduce substances directly into the bloodstream, muscle, or under the skin. Subcutaneous administration, which involves injecting medication into the tissue between the skin and muscle, is a prime example of a parenteral route.

In contrast, oral administration involves taking medication through the mouth, which requires digestion and absorption through the gastrointestinal system. Rectal administration involves placing medication in the rectum, again utilizing the gastrointestinal route. Inhalation involves delivering medication to the lungs and, while it does bypass some aspects of the digestive system, it is not classified as parenteral since it primarily affects local lung tissues. Thus, subcutaneous is the correct choice as it clearly fits the definition of a parenteral route.