Which route would utilize a syringe to inject medication directly into the bloodstream?

The intravenous route is used to inject medication directly into the bloodstream. This method allows for immediate drug action, as the medication enters the circulatory system without any barriers. Intravenous administration is typically utilized in situations where rapid onset of action is critical, such as in emergencies, or when medication cannot be effectively absorbed through other routes.

In contrast, the intradermal route involves injecting medication into the dermis, just below the outer layer of skin, not into the bloodstream. The oral route delivers medication through the digestive system, requiring absorption through the gastrointestinal tract. The subcutaneous route administers medication into the tissue layer between the skin and muscle, which also does not provide direct access to the bloodstream like intravenous injections do. Thus, intravenous administration stands out as the method that directly enters the bloodstream, making it the correct answer.