Suppose that the execution of a process produces the sequence of references to memory pages of the table below.

The Working Set (Working Set) at time t1 and for a time window D = 10 references to memory is:

a) {0, 1, 2, 4, 5, 6, 8, 9, 10}

b) (0, 1, 2, 4, 6, 8, 9, 11, 12}

c) {4, 5, 6, 8, 9, 10, 11, 12}

d) {5, 6, 8, 9, 10}