What symptom is commonly associated with allergic/immunologic responses?

The correct answer is hives, which are also known as urticaria. Hives are a common skin reaction characterized by raised, itchy welts and can appear suddenly due to allergic reactions. When the body encounters an allergen, the immune system releases histamine and other chemicals, leading to this characteristic rash. Hives are often a direct symptom of an allergic response and can occur with other symptoms such as swelling, redness, and irritation.

The other options, while they may occasionally appear in various contexts, are not specific indicators of allergic or immunologic responses. Changes in weight can result from numerous factors including dietary habits or underlying health conditions but do not specifically point to an allergic reaction. Joint stiffness is often associated with autoimmune disorders or inflammatory conditions and is not a typical symptom of an allergy. Tremors may occur due to neurological issues or reactions to medications but are not linked to common allergic responses. Thus, hives are the most accurate and specific symptom indicative of an allergic or immunologic reaction.