Consider the following policies for preventing deadlock in a system with mutually exclusive resources. I. Processes should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released II. The resources are numbered uniquely, and processes are allowed to request for resources only in increasing resource numbers III. The resources are numbered uniquely, and processes are allowed to request for resources only in decreasing resource numbers IV. The resources are numbered uniquely. A process is allowed to request only for a resource with resource number larger than its currently held resources Which of the above policies can be used for preventing deadlock?

Deadlock prevention requires invalidating at least one of the four Coffman conditions (Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait):

• Policy I: Invalids the *Hold and Wait* condition (and allows preemption if resources aren't available). This prevents deadlocks.

• Policy II: By strictly enforcing resource requests in monotonically increasing order of unique IDs, a circular wait chain cannot form, thus invalidating *Circular Wait*.

• Policy III: By strictly enforcing resource requests in monotonically decreasing order of unique IDs, circular wait is also eliminated.

• Policy IV: By allowing requests only for resources with an ID strictly greater than currently held resources, any dependency chain must be strictly monotonic, which prevents *Circular Wait* from occurring.

Since all four policies (I, II, III, and IV) successfully prevent deadlock, (D) is the correct option.