Draining a node is blocked by a PodDisruptionBudget. Its application has two healthy replicas and minAvailable: 2. What is the appropriate explanation?

1. The budget requires two Pods to be evicted simultaneously
2. The node can never be drained while any budget exists
3. PodDisruptionBudgets prevent all involuntary node failures
4. Evicting a healthy replica would violate the budget's minimum availability