In Wait Die System :
- if Old process requests for resource held by young process then Old one waits.
- if Young process requests for resource held by older process then younger process aborts or is rolled back
In Wound-wait System :
- If Old process requests for a resource held by a younger process then Old forces(wounds) the younger one to be rolled back(Preempts) and start again with the same timestamp after a certain delay.
- If young process requests for a certain resource held by older process then young has to wait for old to finish its execution and release the resource.
Hence here in the given question since P has been running for several days so P is the Old Process and Q is the young process.
(a) In wait and die if Old(P) needs a resource held by younger one(Q) then P (Old) should wait.
(b) In wait and die if Young (Q) needs a resource held by Old(P) , then Q(Young) aborts.
(c) In wound-Wait system if Old(P) needs a resource held by younger one(Q) then P(Old) forces Q(Young) to get rolled back or abort.
(d) In Wound-wait system if Young (Q) needs a resource held by Old(P) then Young(Q) has to wait.
Hence answer is (C)
For more details you can refer to : https://stackoverflow.com/questions/32794142/what-is-the-difference-between-wait-die-and-wound-wait