Final answer:
The clinical sign unique to anaphylactic shock is wheezing, as it directly results from contractions of bronchial smooth muscle caused by an allergic reaction. Epinephrine is the drug used to treat anaphylactic shock by countering low blood pressure and bronchoconstriction.
Step-by-step explanation:
The clinical sign unique to anaphylactic shock among the options provided is wheezing. Anaphylactic shock is a systemic and potentially life-threatening type I hypersensitivity reaction. This condition includes a variety of symptoms such as hypotension, dizziness, and pallor, which are not unique to just anaphylaxis.
However, wheezing is distinctive due to the contractions of bronchial smooth muscle caused by systemic mast cell degranulation during the allergic reaction. Other common symptoms during an anaphylactic reaction include swelling of the tongue and throat and a drop in blood pressure that necessitates immediate treatment, often with epinephrine. Epinephrine is the drug used to counteract the effects of anaphylactic shock, raising blood pressure and relaxing bronchial smooth muscle, which can be lifesaving.