Question $3.(3$ points$)$ Consider the following page reference string:

$7,2,3,1,2,5,3,4,6,7,7,1,0,5,4,6,2,3,0,1$

Assuming demand paging with $3$ frames, how many page faults would occur for

the following replacement algorithms? Remember that all frames are initially

empty, so your first unique pages will cost one page fault each.

a$.$ LRU page replacement

b$.$ FIFO page replacement

c$.$ Optimal page replacement