Solution:

Deadlock in an OS occurs only when all four Coffman conditions hold simultaneously:

• Mutual Exclusion: At least one resource is non-shareable.
• Hold and Wait: A process holds one resource and waits for another.
• No Preemption: Resources cannot be forcibly taken; they are released only voluntarily.
• Circular Wait: There exists a cycle of processes each waiting for a resource held by the next.

If any one of these conditions is broken, a deadlock cannot occur. Hence, they are not optional or independent for deadlock—they must all hold together.

✅ Correct Answer: (d) Must hold simultaneously