Which of the instructions $${{\rm I}_1},\,{{\rm I}_2},\,{{\rm I}_3}$$ or $${{\rm I}_4}$$ can legitimately occupy the delay slot without any other program modification?
The $$IF, ID$$ and $$WB$$ stages take one clock cycle each to complete the operation. The number of clock cycles for the $$EX$$ stage depends on the instruction. The $$ADD$$ and $$SUB$$ instructions need $$1$$ clock cycle and the $$MUL$$ instruction needs $$3$$ clock cycles in the $$EX$$ stage. Operand forwarding is used in the pipelined processor. What is the number of clock cycles taken to complete the following sequence of instructions?