Which of the following is a sign of poisoning that may indicate ingestion?

Burns around the mouth are a significant sign that may indicate ingestion of a toxic substance. When a person has ingested a corrosive or caustic material, it can cause direct chemical burns to the tissues of the mouth, lips, and throat. This presents as redness, swelling, or actual burns around the oral cavity, making it a vivid indicator that something harmful has been swallowed.

In contrast, while skin discoloration can occur due to various medical conditions, it is not specifically indicative of poisoning from ingestion. Chest pain can arise from multiple causes, including cardiac issues, and is not necessarily linked to poisoning. Seizures can happen for several reasons, including neurological conditions or trauma, but they do not specifically point to ingestion of poison. Thus, burns around the mouth stand out as a direct and specific sign of potential poisoning through ingestion.