Consider the following MIPS code segment:

sw $t$2,20($$t$0)$

add $t$3,$ $t$1,$ $t$4$

lw $t$1,4($$t$2)$

and $t$2,$ $t$1,$ $t$3$

What is ALU doing during cycle $4$ if forwarding and hazard detection are supported?

Can we rearrange the order of instructions such that the number of cycles is minimized?