Final answer:
Atropine is administered pre-surgery to decrease secretions and prevent the aspiration of these secretions, ensuring a clear airway during the procedure.
Step-by-step explanation:
The best response by the nurse to explain the use of atropine prior to surgery for a fractured hip is option b: "It decreases secretions, makes your mouth dry and prevents aspiration of secretions." Atropine is a muscarinic antagonist that reduces secretions in the mouth and respiratory tract, thus helping to prevent the aspiration of these secretions during surgery. This is crucial as it minimizes the risk of lung complications while under anesthesia. Although atropine also dilates the pupils and affects the autonomic nervous system, these are not the primary reasons for its use in pre-operative care. Hence, the patient is administered atropine to decrease bronchial secretions and to keep the airway clear during surgery.