consider 1) x=x+1 , 2) x=x+1 , 3) x=x+1
case 1: - [ 1) reads x=1 ] preempts -> [ 2) reads x=1 ] preempts -> [ 3) reads x=1 and perform x+1 and stores in x now x = 2 ]
similarly [ 1) comes back performs x+1 and stores x now x=2] , for [ 2) also performs x+1 stores x now x=2]
value of x for [ 1) is 2 ] , [ 2) is 2 ] , [ 3) is 2] = = {2}
case 2:- [ 1) reads x=1 perform x+1 stores in x now x = 2] , [ 2) reads x=2 ] preempts -> [ 3) reads x=2 and perform x+1 and stores x=3]
similarly [ 2) comes back and perform x+1 stores x=3]
value of x for [ 1) is 2] , [ 2) is 3 ], [ 3) is 3] == {2, 3}
case 3:- no one preempts [ 1) reads x= 1 and perform x+1 and stores x now x=2], [2 reads x=2 and perform x+1 and stores x now x =3], [ 3) reads x = 3 and perform x+1 and now x=4]
value of x for [ 1) is 2], [ 2) is 3], [ 3) is 4] == {2,3,4}
question is asked for possible values since possible values are {2}, {2,3}, {2,3,4}
but {2,3,4 } is only option which includes {2} as well as {2,3}
option is b) correct answer