Final answer:
The first sign to suspect malignant hyperthermia is muscle rigidity, particularly in the jaw, which is a severe reaction to general anesthetic drugs. While rapid temperature elevation is a known symptom, it usually appears later in the disorder's progression. Therefore, the correct option is b.
Step-by-step explanation:
The first sign that would assist a nurse in suspecting malignant hyperthermia in a client is B. "Muscle rigidity, especially in the jaw." Malignant hyperthermia is a life-threatening reaction to certain drugs used for general anesthesia. The earliest sign of this condition is often an increased level of carbon dioxide in the blood, but this is frequently followed by muscle rigidity. The rigidity is especially noticeable in the jaw and upper chest. While a rapid elevation in temperature is a hallmark sign, it typically occurs later in the progression of the disorder. Tachycardia and increased blood pressure are also common symptoms but tend to develop after muscle rigidity. Profuse sweating and flushed skin may be symptoms of many conditions and are not as specific to malignant hyperthermia.