What are the three conditions that must be present for deadlock to be possible?

The three conditions that should be present in order for a deadlock to be possible would be first the mutual exclusion which means a process can use one resource at a time. Second is hold and wait which means a process may need to hold the resources while waiting for the assignment of the other resources and lastly is no preemption which means no resource should be remove from a process that is holding it.