Which of the following is a classic deadlock condition?

• A. Paging
• B. Scheduling fairness
• C. Garbage collection
• D. Mutual exclusion

Answer: (D)

Deadlock happens when a group of processes are blocked forever because each one waits for a resource held by another in the group. A classic condition that enables deadlock is mutual exclusion: a resource is assigned to at most one process at a time and cannot be shared. If one process holds a resource and waits for another resource that’s held by a second process, which in turn waits for a resource held by the first, a circular wait forms and progress stops. Mutual exclusion is one of the standard conditions that can lead to deadlock.

The other concepts aren’t deadlock conditions. Paging is about moving memory pages between disk and RAM, scheduling fairness concerns how CPU time is distributed among processes, and garbage collection automatically reclaims unused memory. None of these by themselves define a deadlock scenario.