Suppose the physical memory has four page frames and they are occupied by four pages $(0-3).$ The following table

shows the timestamp when each page is loaded to the frame $($i$.$e$.,$ the "Loaded" column$),$ the timestamp when each

page is last referenced $($i$.$e$.,$ the "Last Ref." column$),$ the recently referenced bit $R$ in the corresponding page table

entry.

Suppose a page fault happens and the system needs to replace a page.

a$)$ If the system uses First$-$In$-$First$-$Out $($FIFO$)$ algorithm, which page is replaced?

b$)$ If the system uses Least$-$Recently$-$Used $($LRU$)$ algorithm, which page is replaced?

c$)$ If the system uses Clock algorithm, and the pages are organized in a circular list of $0-->1-->2-->3-$

$0,$ the clock hand currently points to page $1,$ which page is replaced?

d$)$ If the system uses Clock algorithm, and the pages are organized in a circular list of $0-->1-->2-->3-$

$0,$ the clock hand currently points to page $2,$ which page is replaced?