At $300 \mathrm{~K}$, for a diode current of $1 \mathrm{~mA}$, a certain germanium diode requires a forward bias of $0.1435 \mathrm{~V}$, whereas a certain silicon diode requires a forward bias of $0.178 \mathrm{~V}$. Under the conditions stated above, the closest approximation of the ratio of reverse saturation current in germanium diode to that in silicon diode is
- $1$
- $5$
- $4 \times 10^{3}$
- $8 \times 10^{3}$