Which of the following symptoms might indicate an allergic reaction?

The symptoms that indicate an allergic reaction are characterized by a response from the body's immune system to a substance, known as an allergen. The presence of a rash suggests skin irritation or hives, which are common manifestations of an allergic response. Swelling, particularly of the face, throat, or other areas, can indicate a serious allergic reaction known as anaphylaxis, which may obstruct breathing pathways. Difficulty breathing is another critical indication of a severe allergic reaction, as it can result from swelling of the airways or other respiratory components. Changes in consciousness might also occur due to severe allergic reactions, particularly if they lead to a decrease in oxygen supply to the brain. These symptoms collectively highlight the range of bodily responses that are activated during an allergic reaction, making this option the most indicative of such a condition.