Final answer:
In the case of serious symptoms such as palpitations, chest pain, and a throbbing headache after taking a beta2 agonist for asthma, the drug should be withheld and additional medical orders should be sought.
Step-by-step explanation:
When a client receiving an adrenergic beta2 agonist drug for asthma complains of palpitations, chest pain, and a throbbing headache, the most appropriate nursing action would be A. Withhold the drug until additional orders are obtained. These symptoms could indicate a serious adverse effect and require immediate medical evaluation. It is the responsibility of the nurse to prioritize patient safety and report such adverse reactions to the healthcare provider before continuing the medication.