Final answer:
The correct answer is Local anesthetic.
Step-by-step explanation:
The correct answer is 1) Local anesthetic.
A Bier block is a form of regional anesthesia that is used to numb a specific area of the body, typically an arm or a leg, for surgical procedures. During a Bier block, a local anesthetic is injected into a vein in the affected limb, allowing the anesthetic to circulate and numb the area.