Which type of anesthesia is administered via an anesthetic agent inhaled through the respiratory system?

Inhalational anesthesia is the correct choice as it refers specifically to the administration of anesthetic agents that are inhaled into the respiratory system. This method allows for rapid absorption of the anesthetic into the bloodstream through the lungs, enabling quick induction of anesthesia and precise control over the level of anesthesia during a surgical procedure.

Inhalational agents can target the central nervous system effectively through this route, providing deep anesthesia necessary for both minor and major surgeries. Importantly, this type of anesthesia also allows for quicker recovery times, as the inhaled agents can be easily removed from the body via exhalation.

In contrast, topical and infiltration anesthesia are methods that involve application or injection of anesthetic agents directly onto or into tissues, rather than inhalation. Intravenous anesthesia involves the delivery of anesthetic drugs directly into a vein, bypassing the respiratory system entirely. Each of these methods has its specific uses and benefits, but inhalational anesthesia is distinct in its route of administration through inhalation.