$4\mathrm{.}9$ In this exercise, we examine how data dependences affect execution in the basic $5-$stage pipeline described in Section $4\mathrm{.}5.$ Problems in this exercise refer to the following sequence of instructions: or r$1,$ r$2,$ r$3$

or r$2,$ r$1,$ r$4$

or r$1,$r$1,$ r$2$

Also, assume the follwoing cycle times for each of the options related to forwarding: