Choose proper substitutes for $\mathrm{X}$ and $\mathrm{Y}$ to make the following statement correct Tunnel diode and Avalanche photodiode are operated in $\mathrm{X}$ bias and $\mathrm{Y}$ bias respectively.
- $\mathrm{X}:$ reverse, $\mathrm{Y}:$ reverse
- $\mathrm{X}:$ reverse, $\mathrm{Y}:$ forward
- $\mathrm{X}:$ forward, $\mathrm{Y}:$ reverse
- $\mathrm{X}:$ forward, $\mathrm{Y}:$ forward