The correct answer is option 1.
Concept:
When a process requests for the resource that is been held another process that needs another resource to continue, but is been held by the first process, then it is called a deadlock.
There are 4 conditions necessary for the occurrence of a deadlock.
Mutual Exclusion:
Only one process can hold a resource at a time. In other words, if a process P1 is utilizing a resource R at a specific moment in time, another process P2 cannot hold or utilize the same resource R at that same moment. Process P2 can make a request for that resource R, but it cannot use it at the same time as process P1.
Hold and Wait:
A process can hold several resources at the same time while also requesting resources from another process. A process P1, for example, can have two resources R1 and R2 while also requesting a resource R3 that is currently owned by process P2.
No preemption:
A resource cannot be forcibly removed from a process by another process. If a process P1 is using a resource R, for example, another process P2 cannot take that resource by force. If that's the case, what's the point of using different scheduling algorithms? Process P2 can make a request for the resource R and then wait for process P1 to liberate it.
Circular Wait:
The first process is waiting for the resource held by the second process, and the second process is waiting for the resource held by the third process, and so on. Finally, the last process is waiting for the first process's resource. As a result, each process is waiting for the other to release the resource, with no one releasing their own. Everyone is waiting for the resource to arrive. This is referred to as a circular wait.
Hence the correct answer is Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait.
