Which type of injection is delivered within the muscle?

The correct choice indicates that the type of injection delivered within the muscle is intramuscular. This method involves inserting a needle into a muscle tissue, allowing for the medication to be absorbed into the bloodstream more efficiently than other routes. Intramuscular injections are commonly used for vaccines, hormonal therapies, or medications that require rapid absorption, as the rich blood supply in the muscle tissue facilitates quick entry into the circulatory system.

In contrast, the other methods of injection serve different purposes and involve different anatomical locations. Subcutaneous injections are administered into the fat layer just beneath the skin, which leads to slower absorption compared to intramuscular injections. Intravenous injections, on the other hand, are delivered directly into the bloodstream via a vein, providing immediate effects but not involving muscle tissue. Transdermal administration involves applying medication through the skin for systemic absorption, bypassing the muscle entirely. Each of these methods has specific contexts in which they are appropriate, but for delivering an injection specifically within the muscle, intramuscular is the precise and suitable choice.