Consider an abrupt $p$-junction. Let $V_{\text {in }}$ be the built-in potential of this junction and $\mathrm{V}_{\mathrm{R}}$ be the applied reverse bias. If the junction capacitance $\left(\mathrm{C}_{t}\right)$ is $1 \; \mathrm{pF}$ for
$V_{\text{in}}+V_{\mathrm{R}}=1 \mathrm{~V}$, then for $\mathrm{V}_{\text{in}}+\mathrm{V}_{\mathrm{R}}=4 \mathrm{~V}, \mathrm{C}_{t}$, will be
- $4 \; \mathrm{pF}$
- $2 \; \mathrm{pF}$
- $0.25 \; \mathrm{pF}$
- $0.5 \; \mathrm{pF}$