G following questions using the following code segment: add $t1, $t2, $t3 sub $t4, $t5, $t6 and $t1, $t2, $t4 or $t3, $t2, $t3 What comparisons is the forwarding unit performing during clock cycle 4? Be specific and include the register numbers (e. g., $t2), and where those values are currently located (e. g., ID/EX, EX/MEM, MEM/WB).