How does topical anesthesia achieve its effect?

Topical anesthesia achieves its effect by being applied directly to a body surface. This method works by blocking the nerve signals in the area where it is applied, leading to a loss of sensation locally without affecting the entire body. When topical anesthetics are used, they generally penetrate the skin or mucous membranes to numb the target area, making this method effective for minor surgical procedures, wound care, or dental work, where localized pain control is needed.

In contrast, the other options involve methods of anesthesia that do not align with the principle of topical anesthesia. Injecting anesthetics near nerves refers more to regional anesthesia rather than topical. Inducing loss of sensation throughout the body describes general anesthesia, which affects the entire central nervous system. Using a general anesthetic agent pertains to more invasive procedures requiring unconsciousness, not localized numbing. Thus, the specificity of topical anesthetics to achieve localized numbness makes the option of administration directly to a body surface the correct answer.