Final answer:
A pneumatic tourniquet requires a minimum of 5 minutes of reperfusion time before it is reinflated to ensure adequate blood flow and prevent tissue damage.
Step-by-step explanation:
The pneumatic tourniquet should have a reperfusion time of at least 5 minutes before reinflating it again. This allows the limb to receive adequate blood flow and oxygenation, which is crucial to prevent tissue damage and other complications. Thus, the correct answer is option 4) 5 minutes.