which of the following can prevent deadlocks ?
c) system calls
@Ritu Rahar: how can semaphores prevent deadlock?
Semaphore are used to synchronize the process execution.
See use of semaphore makes mutual exclusion possible which is one of the neccesary condition of deadlock (among other circular wait, hold and wait, no preemption) so use of semaphore could cause a deadlock instead…:)