Which patient would most likely benefit from the administration of activated charcoal?

The administration of activated charcoal is most beneficial for a patient who has ingested a potentially toxic substance. Activated charcoal works by adsorbing the toxins in the gastrointestinal tract, preventing their absorption into the bloodstream. It is particularly effective when used within a few hours of the ingestion of certain drugs or poisons, reducing the overall toxicity and potential harm to the patient.

In contrast, a patient with an upper respiratory infection typically requires supportive care and does not benefit from activated charcoal, as this condition is not related to toxin ingestion. Similarly, nausea and vomiting after eating can result from various causes including food poisoning, but activated charcoal is not a standard treatment for these symptoms unless specific toxic ingestion is confirmed. Finally, in the case of a patient in cardiac arrest, timely interventions focused on resuscitation and addressing the underlying cause take priority, with activated charcoal having no relevant role in this scenario. Thus, the correct answer underlines the specific context where activated charcoal is an appropriate intervention.