The efficiency of the reversible heat engine is ${\mathrm{η}}_r$ and that of irreversible heat engine is ${\mathrm{η}}_{\mathrm{i}}$. Which of the following relations is correct

• A

  ${\mathrm{η}}_{\mathrm{r}}>{\mathrm{η}}_{\mathrm{i}}$

• B

  ${\mathrm{η}}_{\mathrm{r}}<{\mathrm{η}}_{\mathrm{i}}$

• C

  ${\mathrm{η}}_{\mathrm{f}}={\mathrm{η}}_{\mathrm{i}}$

• D

  ${\mathrm{η}}_{\mathrm{r}}$is greater than 1 and ${\mathrm{η}}_{\mathrm{i}}$ is less than 1